diff --git a/Contrib/METU-NCC/Applied_Math/fourier/Omega.pg b/Contrib/METU-NCC/Applied_Math/fourier/Omega.pg
index 217a953fd7..8caf0e7bd5 100644
--- a/Contrib/METU-NCC/Applied_Math/fourier/Omega.pg
+++ b/Contrib/METU-NCC/Applied_Math/fourier/Omega.pg
@@ -58,6 +58,10 @@ $wj   = Complex(cos(2*pi*$j/$N),-sin(2*pi*$j/$N));
 Context("Numeric");
 Context()->variables->are('i'=>"Real");
 Context()->functions->disable('Trig');
+Context()->flags->set(
+  tolerance => 0.001,
+  tolType => "absolute",
+);
 
 $w    = Formula($w->string   );
 $wbar = Formula($wbar->string);
diff --git a/Contrib/METU-NCC/Applied_Math/trusses/truss-2node-4bar.pg b/Contrib/METU-NCC/Applied_Math/trusses/truss-2node-4bar.pg
index c19d333113..edde467be6 100644
--- a/Contrib/METU-NCC/Applied_Math/trusses/truss-2node-4bar.pg
+++ b/Contrib/METU-NCC/Applied_Math/trusses/truss-2node-4bar.pg
@@ -13,11 +13,11 @@
 
 DOCUMENT() ;        
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "parserVectorUtils.pl",
-  "PGcourse.pl"
-);
+"PGstandard.pl",
+"MathObjects.pl",
+"parserVectorUtils.pl",
+"PGcourse.pl"
+) ;
 TEXT(beginproblem());
 
 #######################################
diff --git a/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar.pg b/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar.pg
index c9564886fa..732754d34a 100644
--- a/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar.pg
+++ b/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar.pg
@@ -13,15 +13,14 @@
 
 DOCUMENT() ;        
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGchoicemacros.pl",
-  "parserPopUp.pl",
-  "unionTables.pl",
-  "MatrixCheckers.pl",
-  "PGcourse.pl"
-);
+"PGstandard.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
+"PGchoicemacros.pl",
+"parserPopUp.pl",
+"unionTables.pl",
+"MatrixCheckers.pl"
+) ;
 TEXT(beginproblem());
 
 #######################################
diff --git a/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar_diamond.pg b/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar_diamond.pg
index e0adfa5472..b90fcac774 100644
--- a/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar_diamond.pg
+++ b/Contrib/METU-NCC/Applied_Math/trusses/truss-3node-4bar_diamond.pg
@@ -13,16 +13,15 @@
 
 DOCUMENT() ;        
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGchoicemacros.pl",
-  "parserPopUp.pl",
-  "unionTables.pl",
-  "MatrixCheckers.pl",
-  "PGmatrixmacros.pl",
-  "PGcourse.pl"
-);
+"PGstandard.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
+"PGchoicemacros.pl",
+"parserPopUp.pl",
+"unionTables.pl",
+"MatrixCheckers.pl",
+"PGmatrixmacros.pl"
+) ;
 TEXT(beginproblem());
 
 #######################################
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-cx.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-cx.pg
index 538d58abb0..8e72856a37 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-cx.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-cx.pg
@@ -25,7 +25,6 @@ loadMacros(
   "MathObjects.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-rep.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-rep.pg
index a6e1c785e3..6b19c8518e 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-rep.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog-rep.pg
@@ -25,7 +25,6 @@ loadMacros(
   "MathObjects.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog.pg
index 6a97f002cf..9959945a43 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system-nonhomog.pg
@@ -25,7 +25,6 @@ loadMacros(
   "MathObjects.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-cx.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-cx.pg
index 5b9c00ad0d..a1eda36ccd 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-cx.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-cx.pg
@@ -21,12 +21,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGmatrixmacros.pl",
-  "parserMultiAnswer.pl",
-  "unionTables.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"MathObjects.pl",
+"PGmatrixmacros.pl",
+"parserMultiAnswer.pl",
+"PGcourse.pl",
+"unionTables.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-rep.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-rep.pg
index 9715fdac26..ef62b801b8 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-rep.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln-rep.pg
@@ -21,12 +21,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGmatrixmacros.pl",
-  "parserMultiAnswer.pl",
-  "unionTables.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"MathObjects.pl",
+"PGmatrixmacros.pl",
+"parserMultiAnswer.pl",
+"PGcourse.pl",
+"unionTables.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln.pg b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln.pg
index 25d469e1c2..77044098a4 100644
--- a/Contrib/METU-NCC/Diff_Eq/2x2-system_soln.pg
+++ b/Contrib/METU-NCC/Diff_Eq/2x2-system_soln.pg
@@ -21,12 +21,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGmatrixmacros.pl",
-  "parserMultiAnswer.pl",
-  "unionTables.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"MathObjects.pl",
+"PGmatrixmacros.pl",
+"parserMultiAnswer.pl",
+"PGcourse.pl",
+"unionTables.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/3x3-system-convert.pg b/Contrib/METU-NCC/Diff_Eq/3x3-system-convert.pg
index 09b9336baf..5b71ecebe8 100644
--- a/Contrib/METU-NCC/Diff_Eq/3x3-system-convert.pg
+++ b/Contrib/METU-NCC/Diff_Eq/3x3-system-convert.pg
@@ -17,7 +17,6 @@ loadMacros(
   "MathObjects.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 Context("Numeric");
diff --git a/Contrib/METU-NCC/Diff_Eq/bvp-eigen.pg b/Contrib/METU-NCC/Diff_Eq/bvp-eigen.pg
index 4a12dc72a0..35cf1554fe 100644
--- a/Contrib/METU-NCC/Diff_Eq/bvp-eigen.pg
+++ b/Contrib/METU-NCC/Diff_Eq/bvp-eigen.pg
@@ -10,12 +10,11 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "unionLists.pl",
-  "PGchoicemacros.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "unionLists.pl",
+   "PGchoicemacros.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/bvp.pg b/Contrib/METU-NCC/Diff_Eq/bvp.pg
index 6ea5caa1b9..29eb759a77 100644
--- a/Contrib/METU-NCC/Diff_Eq/bvp.pg
+++ b/Contrib/METU-NCC/Diff_Eq/bvp.pg
@@ -10,14 +10,13 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "parserMultiAnswer.pl",
-  "unionLists.pl",
-  "PGchoicemacros.pl",
-  "contextFraction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "parserMultiAnswer.pl",
+   "unionLists.pl",
+   "PGchoicemacros.pl",
+   "contextFraction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/fourier-cos.pg b/Contrib/METU-NCC/Diff_Eq/fourier-cos.pg
index 19debcafb2..8c90b13c59 100644
--- a/Contrib/METU-NCC/Diff_Eq/fourier-cos.pg
+++ b/Contrib/METU-NCC/Diff_Eq/fourier-cos.pg
@@ -21,7 +21,6 @@ loadMacros(
   "PGgraphmacros.pl",
   "answerHints.pl",
   "unionLists.pl",
-  "PGcourse.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/fourier-sin.pg b/Contrib/METU-NCC/Diff_Eq/fourier-sin.pg
index a703be6039..c704c784c6 100644
--- a/Contrib/METU-NCC/Diff_Eq/fourier-sin.pg
+++ b/Contrib/METU-NCC/Diff_Eq/fourier-sin.pg
@@ -21,7 +21,6 @@ loadMacros(
   "PGgraphmacros.pl",
   "answerHints.pl",
   "unionLists.pl",
-  "PGcourse.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/fourier-sin_cos.pg b/Contrib/METU-NCC/Diff_Eq/fourier-sin_cos.pg
index 29219c1876..e5c9fdea9f 100644
--- a/Contrib/METU-NCC/Diff_Eq/fourier-sin_cos.pg
+++ b/Contrib/METU-NCC/Diff_Eq/fourier-sin_cos.pg
@@ -21,7 +21,6 @@ loadMacros(
   "PGgraphmacros.pl",
   "answerHints.pl",
   "unionLists.pl",
-  "PGcourse.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/high-order-linear_1.pg b/Contrib/METU-NCC/Diff_Eq/high-order-linear_1.pg
index 74a5623562..a36d1ab0a6 100644
--- a/Contrib/METU-NCC/Diff_Eq/high-order-linear_1.pg
+++ b/Contrib/METU-NCC/Diff_Eq/high-order-linear_1.pg
@@ -18,7 +18,6 @@ loadMacros(
   "PGmatrixmacros.pl",
   "MathObjects.pl",
   "parserMultiAnswer.pl",
-  "PGcourse.pl"
 );
 
 #####################################
diff --git a/Contrib/METU-NCC/Diff_Eq/impulse-response.pg b/Contrib/METU-NCC/Diff_Eq/impulse-response.pg
index 4ef0068ce2..9fb9e1c529 100644
--- a/Contrib/METU-NCC/Diff_Eq/impulse-response.pg
+++ b/Contrib/METU-NCC/Diff_Eq/impulse-response.pg
@@ -20,7 +20,6 @@ loadMacros(
   "PGmatrixmacros.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-inv_I.pg b/Contrib/METU-NCC/Diff_Eq/laplace-inv_I.pg
index 583bdbf78e..29cc5c3c71 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-inv_I.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-inv_I.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-inv_II.pg b/Contrib/METU-NCC/Diff_Eq/laplace-inv_II.pg
index abb925b60c..5a21284542 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-inv_II.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-inv_II.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-inv_III.pg b/Contrib/METU-NCC/Diff_Eq/laplace-inv_III.pg
index 76d1eb5a14..c1819275d3 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-inv_III.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-inv_III.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-inv_random.pg b/Contrib/METU-NCC/Diff_Eq/laplace-inv_random.pg
index 83312a552c..9538d321d2 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-inv_random.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-inv_random.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_t.pg b/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_t.pg
index 347dba764e..e046a29279 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_t.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_t.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_trig.pg b/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_trig.pg
index f5f9923738..e9a1077329 100644
--- a/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_trig.pg
+++ b/Contrib/METU-NCC/Diff_Eq/laplace-step_exp_trig.pg
@@ -16,13 +16,12 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGunion.pl",
-  "answerHints.pl",
-  "parserAssignment.pl",
-  "parserFunction.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",
+   "MathObjects.pl",
+   "PGunion.pl",
+   "answerHints.pl",
+   "parserAssignment.pl",
+   "parserFunction.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog.pg b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog.pg
index 9c0771ad0d..6fd0341758 100644
--- a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog.pg
+++ b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog.pg
@@ -21,7 +21,6 @@ loadMacros(
   "parserMultiAnswer.pl",
   "answerHints.pl",
   "extraAnswerEvaluators.pl",  # needed for equation_cmp
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_euler.pg b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_euler.pg
index 80dd4fa341..649313286d 100644
--- a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_euler.pg
+++ b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_euler.pg
@@ -21,7 +21,6 @@ loadMacros(
   "parserMultiAnswer.pl",
   "answerHints.pl",
   "extraAnswerEvaluators.pl",  # needed for equation_cmp
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_undet-coef.pg b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_undet-coef.pg
index b7d29bba5c..1c00e4a667 100644
--- a/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_undet-coef.pg
+++ b/Contrib/METU-NCC/Diff_Eq/linear-nonhomog_undet-coef.pg
@@ -21,7 +21,6 @@ loadMacros(
   "parserMultiAnswer.pl",
   "answerHints.pl",
   "extraAnswerEvaluators.pl",  # needed for equation_cmp
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Diff_Eq/pde-heat1.pg b/Contrib/METU-NCC/Diff_Eq/pde-heat1.pg
index eb1dc34225..e5a39f2eb0 100644
--- a/Contrib/METU-NCC/Diff_Eq/pde-heat1.pg
+++ b/Contrib/METU-NCC/Diff_Eq/pde-heat1.pg
@@ -17,13 +17,12 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "parserMultiAnswer.pl",
-  "unionLists.pl",
-  "scaffold.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "parserMultiAnswer.pl",
+   "unionLists.pl",
+   "scaffold.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/pde-heat2.pg b/Contrib/METU-NCC/Diff_Eq/pde-heat2.pg
index 44e731a998..b02526df0c 100644
--- a/Contrib/METU-NCC/Diff_Eq/pde-heat2.pg
+++ b/Contrib/METU-NCC/Diff_Eq/pde-heat2.pg
@@ -17,13 +17,12 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "parserMultiAnswer.pl",
-  "unionLists.pl",
-  "scaffold.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "parserMultiAnswer.pl",
+   "unionLists.pl",
+   "scaffold.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/pde-heat3.pg b/Contrib/METU-NCC/Diff_Eq/pde-heat3.pg
index 110643b2ab..acd7e2b8fb 100644
--- a/Contrib/METU-NCC/Diff_Eq/pde-heat3.pg
+++ b/Contrib/METU-NCC/Diff_Eq/pde-heat3.pg
@@ -17,13 +17,12 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "parserMultiAnswer.pl",
-  "unionLists.pl",
-  "scaffold.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "parserMultiAnswer.pl",
+   "unionLists.pl",
+   "scaffold.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/pde-separation.pg b/Contrib/METU-NCC/Diff_Eq/pde-separation.pg
index 588a016b44..94561a711e 100644
--- a/Contrib/METU-NCC/Diff_Eq/pde-separation.pg
+++ b/Contrib/METU-NCC/Diff_Eq/pde-separation.pg
@@ -12,12 +12,11 @@
 DOCUMENT();      
 
 loadMacros(
-  "PGstandard.pl",   
-  "MathObjects.pl",
-  "answerHints.pl",
-  "parserMultiAnswer.pl",
-  "unionLists.pl",
-  "PGcourse.pl"
+   "PGstandard.pl",   
+   "MathObjects.pl",
+   "answerHints.pl",
+   "parserMultiAnswer.pl",
+   "unionLists.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Diff_Eq/pplane-match_1.pg b/Contrib/METU-NCC/Diff_Eq/pplane-match_1.pg
index 3fdd24905d..f00c5ba2b2 100644
--- a/Contrib/METU-NCC/Diff_Eq/pplane-match_1.pg
+++ b/Contrib/METU-NCC/Diff_Eq/pplane-match_1.pg
@@ -17,12 +17,11 @@
 DOCUMENT(); 
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "PGgraphmacros.pl",
-  "PGunion.pl",
-  "imageChoice.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"MathObjects.pl",
+"PGgraphmacros.pl",
+"PGunion.pl",
+"imageChoice.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Linear_Algebra/2.1.8.pg b/Contrib/METU-NCC/Linear_Algebra/2.1.8.pg
new file mode 100644
index 0000000000..8fc9cea7d2
--- /dev/null
+++ b/Contrib/METU-NCC/Linear_Algebra/2.1.8.pg
@@ -0,0 +1,102 @@
+# DESCRIPTION
+# Converting matrix equation to system of equations
+# ENDDESCRIPTION
+## DBsubject(Linear algebra)
+## DBchapter(Matrices)
+## DBsection(Matrix algebra)
+## Author(Benjamin Walter)
+## Level(3)
+## KEYWORDS('linear algebra','vectors')
+## MO(1)
+## Static(0)
+
+DOCUMENT();
+loadMacros(
+"PG.pl",
+"PGbasicmacros.pl",
+"PGchoicemacros.pl",
+"PGanswermacros.pl",
+"PGgraphmacros.pl",
+"PGmatrixmacros.pl", 
+"PGnumericalmacros.pl",
+"PGauxiliaryFunctions.pl",
+"PGmorematrixmacros.pl",
+"MathObjects.pl",
+"freemanMacros.pl",
+"PGasu.pl",
+"PG.pl",
+
+);
+
+# make sure we're in the context we want
+Context("Numeric")->variables->are(x=>'Real',y=>'Real');
+$v11=random(1,9,1);
+$v12=random(-9,9,1);
+$v13=random(-9,9,1);
+$v21=random(-9,9,1);
+$v22=random(1,9,1);
+$v23=random(-9,9,1);
+if($v11*$v22==$v12*$v21){$v22=-$v22;}
+$v31=random(1,9,1)*random(-1,1,2);
+$v32=random(-9,9,1);
+$v33=random(1,9,1);
+if($v11*$v22*$v33+$v21*$v32*$v13+$v31*$v12*$v23-$v13*$v22*$v31-$v23*$v32*$v11-$v33*$v12*$v21==0){$v33=-$v33;}
+
+
+TEXT(beginproblem());
+$showPartialCorrectAnswers = 1;
+BEGIN_TEXT
+$PAR
+Consider the following vector equation. 
+$PAR
+\[ 
+ \left[\begin{array}{rr} 
+    $v11 & $v12  \\
+    $v21 & $v22  \\
+    $v31 & $v32 
+ \end{array}\right] \mathbf{x} = 
+ \left[\begin{array}{r}
+    $v13 \\
+    $v23 \\
+    $v33
+ \end{array}\right]
+\]
+$PAR
+Express the vector equation as a system of linear equations.  (Order your equations from the top.) 
+$PAR
+The first equation is \{ans_rule(5)\}\(x_1+\) \{ans_rule(5)\}\(x_2\) =  \{ans_rule(5)\}.
+$PAR
+The second equation is \{ans_rule(5)\}\(x_1+\) \{ans_rule(5)\}\(x_2\) =  \{ans_rule(5)\}.
+$PAR
+The third equation is \{ans_rule(5)\}\(x_1+\) \{ans_rule(5)\}\(x_2\) =  \{ans_rule(5)\}.
+$PAR
+$PAR
+END_TEXT
+Context()->normalStrings;
+
+ANS(num_cmp($v11)  );
+ANS(num_cmp($v12)  );
+ANS(num_cmp($v13)  );
+ANS(num_cmp($v21)  );
+ANS(num_cmp($v22)  );
+ANS(num_cmp($v23)  );
+ANS(num_cmp($v31)  );
+ANS(num_cmp($v32)  );
+ANS(num_cmp($v33)  );
+
+
+Context()->texStrings;
+SOLUTION(EV3(<<'END_SOLUTION'));
+$PAR 
+SOLUTION 
+$PAR
+
+Each row of the vector equation becomes a linear equation.
+$PAR
+
+
+
+END_SOLUTION
+Context()->normalStrings;
+
+ENDDOCUMENT();
diff --git a/Contrib/METU-NCC/Linear_Algebra/2x2-eig_def.pg b/Contrib/METU-NCC/Linear_Algebra/2x2-eig_def.pg
index e3636fc4f9..576bcd2780 100644
--- a/Contrib/METU-NCC/Linear_Algebra/2x2-eig_def.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/2x2-eig_def.pg
@@ -22,11 +22,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval.pg b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval.pg
index bdfc53029b..96476d7160 100644
--- a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval.pg
@@ -20,11 +20,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_2.pg b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_2.pg
index 89763c1243..285f2a9f98 100644
--- a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_2.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_2.pg
@@ -20,11 +20,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_cx.pg b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_cx.pg
index f63267b469..899c9a28b3 100644
--- a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_cx.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_cx.pg
@@ -20,11 +20,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_rep.pg b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_rep.pg
index 99e1bf3d90..f9f91234ee 100644
--- a/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_rep.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/2x2-eigenval_rep.pg
@@ -20,11 +20,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-2d_eig.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-2d_eig.pg
index 1a1562bf19..c70c4dd06c 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-2d_eig.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-2d_eig.pg
@@ -18,12 +18,11 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "MatrixUnits.pl",              # Needed for GL3Z()
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGmatrixmacros.pl",
-  "PGcourse.pl"
+ "MatrixUnits.pl",              # Needed for GL3Z()
+ "MathObjects.pl",
+ "parserMultiAnswer.pl",
+ "PGmatrixmacros.pl",
+ "PGstandard.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def-small.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def-small.pg
index 6679284abf..9fb41d73ab 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def-small.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def-small.pg
@@ -22,11 +22,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def.pg
index 11f374ea91..614eebfa82 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eig_def.pg
@@ -22,11 +22,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_0.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_0.pg
index 4b6f302321..ab3ed1bc65 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_0.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_0.pg
@@ -21,11 +21,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_1.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_1.pg
index b6991546e0..096fc068f3 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_1.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_1.pg
@@ -21,11 +21,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_2.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_2.pg
index 84d3a9cb06..cc7ff7395c 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_2.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_2.pg
@@ -21,11 +21,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_3.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_3.pg
index 029d6e203d..ef655db628 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_3.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-eigenval_3.pg
@@ -23,11 +23,11 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
+"PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig.pg
index c3c33a9384..228b615065 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig.pg
@@ -18,12 +18,11 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "MatrixUnits.pl",              # Needed for GL3Z()
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGmatrixmacros.pl",
-  "PGcourse.pl"
+ "MatrixUnits.pl",              # Needed for GL3Z()
+ "MathObjects.pl",
+ "parserMultiAnswer.pl",
+ "PGmatrixmacros.pl",
+ "PGstandard.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig_prop.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig_prop.pg
index 741166b8d4..9aad7d01ea 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig_prop.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_eig_prop.pg
@@ -27,7 +27,6 @@ loadMacros(
   "MathObjects.pl",
   "parserMultiAnswer.pl",
   "answerHints.pl",
-  "PGcourse.pl"
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_gen_eig.pg b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_gen_eig.pg
index c0ad29dfcf..81f88f94a3 100644
--- a/Contrib/METU-NCC/Linear_Algebra/3x3-gen_gen_eig.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/3x3-gen_gen_eig.pg
@@ -18,12 +18,11 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "MatrixUnits.pl",              # Needed for GL3Z()
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+ "MatrixUnits.pl",              # Needed for GL3Z()
+ "PGstandard.pl",
+ "PGmatrixmacros.pl",
+ "MathObjects.pl",
+ "parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/4x4-det_block.pg b/Contrib/METU-NCC/Linear_Algebra/4x4-det_block.pg
index b2cc8c2768..c27cbd7dac 100644
--- a/Contrib/METU-NCC/Linear_Algebra/4x4-det_block.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/4x4-det_block.pg
@@ -12,15 +12,15 @@
 ## Level(2)
 ## MO(1)
 ## Static(0)
-## KEYWORDS('algebra', 'matrix operation', 'matrix', 'determinant')
+# KEYWORDS('algebra', 'matrix operation', 'matrix', 'determinant')
 
 DOCUMENT();        # This should be the first executable line in the problem.
 
 loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "MathObjects.pl",
-  "PGcourse.pl",
+"PGstandard.pl",
+"PGchoicemacros.pl",
+"MathObjects.pl",
+"PGcourse.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Linear_Algebra/4x4-det_triangle.pg b/Contrib/METU-NCC/Linear_Algebra/4x4-det_triangle.pg
index f4d5cd10a9..065f19d12f 100644
--- a/Contrib/METU-NCC/Linear_Algebra/4x4-det_triangle.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/4x4-det_triangle.pg
@@ -17,10 +17,10 @@
 DOCUMENT();        # This should be the first executable line in the problem.
 
 loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "MathObjects.pl",
-  "PGcourse.pl",
+"PGstandard.pl",
+"PGchoicemacros.pl",
+"MathObjects.pl",
+"PGcourse.pl",
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/Linear_Algebra/4x4-eig_def.pg b/Contrib/METU-NCC/Linear_Algebra/4x4-eig_def.pg
index 36262494f8..ef39f8641d 100644
--- a/Contrib/METU-NCC/Linear_Algebra/4x4-eig_def.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/4x4-eig_def.pg
@@ -22,11 +22,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "MathObjects.pl",
-  "parserMultiAnswer.pl",
-  "PGcourse.pl"
+"PGstandard.pl",
+"PGmatrixmacros.pl",
+"MathObjects.pl",
+"parserMultiAnswer.pl",
 );
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Intersect_plane_3.pg b/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Intersect_plane_3.pg
index 55f45993a3..e37f540e15 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Intersect_plane_3.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Intersect_plane_3.pg
@@ -142,6 +142,9 @@ $PAR
 $PAR
 \(\qquad \displaystyle B = \bigl\lbrace $vars\ \Big|\ \ $Beqn=$Bd \bigr\rbrace\)
 $PAR
+Note: for this problem to be checked correctly, all of your answers must be 
+points.  If any of your answers are numbers or words then none of your 
+answers will be checked.
 
 \{$MAns->ans_rule(10);\} $BR 
 \{$MAns->ans_rule(10);\} $BR
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Minus_P2.pg b/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Minus_P2.pg
index 48c8e35330..70598f5615 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Minus_P2.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week1/Set-Minus_P2.pg
@@ -40,20 +40,20 @@ Context()->variables->are(x=>"Real");
 $i = random(0,1);
 @ineq = ("\le","\ge");
 
-($a,$c) = pick(2,(-2..2));
+do { ($a,$c) = pick(2,(-2..2)); } until ($c!=0);
 do { $b = non_zero_random(-2,2) } until ($b!=$a);
 
 $d = ($b-$a)+$c + (($i==0) ? random(1,3) : -random(1,3));
 
-$m1 = (($i==0) xor ($b-$a < 0))
-      ?  ceil(($d-$c)/($b-$a))+1 
-      : floor(($d-$c)/($b-$a))-1;
-$m2 = (($i==0) xor ($b*($b-$a) < 0))
-      ?  ceil(($d-$c)/($b*($b-$a)))+1 
-      : floor(($d-$c)/($b*($b-$a)))-1;
+$m1 = (($i==0) xor ($c-$a < 0))
+      ? floor(($d-$b)/($c-$a))-1 
+      :  ceil(($d-$b)/($c-$a))+1;
+$m2 = (($i==0) xor ($c*($c-$a) < 0))
+      ? floor(($d-$b)/($c*($c-$a)))-1 
+      :  ceil(($d-$b)/($c*($c-$a)))+1;
 
-$ans1 = Formula("$m1*x+($c-$m1*$a)")->reduce;
-$ans2 = Formula("$m2*x(x-$a)+$c")->reduce;
+$ans1 = Formula("$m1*x+($b-$m1*$a)")->reduce;
+$ans2 = Formula("$m2*x(x-$a)+$b")->reduce;
 
 $MAns = MultiAnswer($ans1, $ans2
 )->with(
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week11/reduce-4x5r3.pg b/Contrib/METU-NCC/Linear_Algebra/Week11/reduce-4x5r3.pg
index 0d216e81bd..a97cf20e31 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week11/reduce-4x5r3.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week11/reduce-4x5r3.pg
@@ -60,6 +60,9 @@ foreach my $i (0 .. $m-1) {
                   ($j==0)  ? non_zero_random(-1,1) : non_zero_random(-2,2);
   }
 }
+while ( Vector(@{$La[$m-1]}[0..($m-2)])->isParallel(Vector(@{$La[$m-2]}[0..($m-2)])) ) {
+  foreach my $j (0 .. $m-2) { $La[$m-1][$j] = non_zero_random(-2,2); }
+}
 my $Lm = Matrix(@La);
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_h.pg b/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_h.pg
index 93fe446a71..d5107e6e70 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_h.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_h.pg
@@ -97,6 +97,9 @@ foreach my $i (0 .. $m-1) {
                   ($j==0)  ? non_zero_random(-1,1) : non_zero_random(-2,2);
   }
 }
+while ( Vector(@{$La[$m-1]}[0..($m-2)])->isParallel(Vector(@{$La[$m-2]}[0..($m-2)])) ) {
+  foreach my $j (0 .. $m-2) { $La[$m-1][$j] = non_zero_random(-2,2); }
+}
 my $Lm = Matrix(@La);
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_nh.pg b/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_nh.pg
index 3a01498dfd..2bbafea5ec 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_nh.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week11/solve-4x5r3_nh.pg
@@ -96,6 +96,9 @@ foreach my $i (0 .. $m-1) {
                   ($j==0)  ? non_zero_random(-1,1) : non_zero_random(-2,2);
   }
 }
+while ( Vector(@{$La[$m-1]}[0..($m-2)])->isParallel(Vector(@{$La[$m-2]}[0..($m-2)])) ) {
+  foreach my $j (0 .. $m-2) { $La[$m-1][$j] = non_zero_random(-2,2); }
+}
 my $Lm = Matrix(@La);
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/Week5/Intersect_basis-R.pg b/Contrib/METU-NCC/Linear_Algebra/Week5/Intersect_basis-R.pg
index d6a87cc77b..07060198d3 100644
--- a/Contrib/METU-NCC/Linear_Algebra/Week5/Intersect_basis-R.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/Week5/Intersect_basis-R.pg
@@ -32,7 +32,7 @@ sub pick {
 }
 
 
-sub gcd {
+sub GCD {
   my $a = abs(shift); my $b = abs(shift);
   ($a,$b) = ($b,$a) if $a < $b;
   return $a if $b == 0;
@@ -79,20 +79,20 @@ foreach (0..3) {
 }
 
 my $gcd;
-$gcd = 0;
-foreach (0..$#v) { $gcd = gcd($v[$_],$gcd); }
+$gcd = $v[0];
+foreach (1..$#v) { $gcd = GCD($v[$_],$gcd); }
 foreach (0..$#v) { $v[$_] = $v[$_]/$gcd; }
-$gcd = 0;
-foreach (0..$#w) { $gcd = gcd($w[$_],$gcd); }
+$gcd = $w[0];
+foreach (1..$#w) { $gcd = GCD($w[$_],$gcd); }
 foreach (0..$#w) { $w[$_] = $w[$_]/$gcd; }
-$gcd = 0;
-foreach (0..$#wa) { $gcd = gcd($wa[$_],$gcd); }
+$gcd = $wa[0];
+foreach (1..$#wa) { $gcd = GCD($wa[$_],$gcd); }
 foreach (0..$#wa) { $wa[$_] = $wa[$_]/$gcd; }
-$gcd = 0;
-foreach (0..$#vp) { $gcd = gcd($vp[$_],$gcd); }
+$gcd = $vp[0];
+foreach (1..$#vp) { $gcd = GCD($vp[$_],$gcd); }
 foreach (0..$#vp) { $vp[$_] = $vp[$_]/$gcd; }
-$gcd = 0;
-foreach (0..$#wp) { $gcd = gcd($wp[$_],$gcd); }
+$gcd = $wp[0];
+foreach (1..$#wp) { $gcd = GCD($wp[$_],$gcd); }
 foreach (0..$#wp) { $wp[$_] = $wp[$_]/$gcd; }
 
 
diff --git a/Contrib/METU-NCC/Linear_Algebra/solve_lower-triangular.pg b/Contrib/METU-NCC/Linear_Algebra/solve_lower-triangular.pg
index 6404a786da..68c9475253 100644
--- a/Contrib/METU-NCC/Linear_Algebra/solve_lower-triangular.pg
+++ b/Contrib/METU-NCC/Linear_Algebra/solve_lower-triangular.pg
@@ -11,11 +11,12 @@
 DOCUMENT();        # This should be the first executable line in the problem.
 
 loadMacros(
-  "PGstandard.pl",
-  "PGmatrixmacros.pl",
-  "PGmorematrixmacros.pl",
-  "MathObjects.pl",
-  "PGcourse.pl"
+ "PG.pl",
+ "PGbasicmacros.pl",
+ "PGmatrixmacros.pl",
+ "PGmorematrixmacros.pl",
+ "PGstandard.pl",
+ "MathObjects.pl"
 );
 
 TEXT(beginproblem());
diff --git a/Contrib/METU-NCC/MAT100/23a_Degree-radian.pg b/Contrib/METU-NCC/MAT100/23a_Degree-radian.pg
deleted file mode 100644
index 710d86a0ee..0000000000
--- a/Contrib/METU-NCC/MAT100/23a_Degree-radian.pg
+++ /dev/null
@@ -1,92 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Convert from degrees to radians (5 conversions) 
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Trigonometry)
-## DBchapter(Geometric and algebraic foundations for trigonometry)
-## DBsection(Radians, converting radians & degrees)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-DOCUMENT();        # This should be the first executable line in the problem.
-
-loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "PGasu.pl",
-  "PGcourse.pl",
-  "MathObjects.pl",
-  "contextFraction.pl"
-);
-
-sub pick {
-  my ($k, @in) = @_;
-  my @out = ();
-  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
-  @out; 
-}
-
-TEXT(beginproblem());
-$showPartialCorrectAnswers = 1;
-Context("Fraction-NoDecimals");
-
-my @c = (
-  (-11,-7,-5,5,7,11)[random(0,5)], 
-  (-7, -5,-3,3,5, 7)[random(0,5)], 
-  (-8,-7,-5,-4,-2,2,4,5,7,8)[random(0,9)],
-  (-7,-5,-3,3,5,7)[random(0,5)],
-  (-5,-4,-3,3,4,5)[random(0,5)],
-);
-
-@r = (
- Compute(($c[0]%12)."*pi/6")->reduce,
- Compute(($c[1]%8)."*pi/4")->reduce,
- Compute(($c[2]%6)."*pi/3")->reduce,
- Compute(($c[3]%4)."*pi/2")->reduce, 
- Compute(($c[4]%2)."*pi/1")->reduce
-);
-
-@d = (
- Compute("30*$c[0]"),
- Compute("45*$c[1]"),
- Compute("60*$c[2]"),
- Compute("90*$c[3]"),
- Compute("180*$c[4]")
-);
-
-foreach (0..$#c) { $s[$_] = ($c[$_] < 0) ? "" : "\phantom{-}"; }
-
-@i = pick(5,(0..4));
-
-Context()->texStrings;
-BEGIN_TEXT
-
-Convert the following $BBOLD degree $EBOLD measures to $BBOLD radians. $EBOLD$BR
-(Write your answers as angles \(0 \le \theta < 2\pi \).  Write as a fraction
-using \(\fbox{pi}\) for \(\pi\).)
-
-END_TEXT
-for ($j=0; $j <= $#d; $j++) {
-BEGIN_TEXT
-
-$PAR $SPACE $SPACE
-\($s[$i[$j]]$d[$i[$j]]\ \text{degrees}\ = \ \) 
-\{ ans_rule(10) \} \(\text{radians}\)
-
-END_TEXT
-}
-
-Context()->normalStrings;
-
-for ($j=0; $j <= $#r; $j++) {
-  ANS( $r[$i[$j]]->cmp() );
-}
-
-ENDDOCUMENT();        # This should be the last executable line in the problem.
-
diff --git a/Contrib/METU-NCC/MAT100/23b_Radian-degree.pg b/Contrib/METU-NCC/MAT100/23b_Radian-degree.pg
deleted file mode 100644
index 38ed9a74dc..0000000000
--- a/Contrib/METU-NCC/MAT100/23b_Radian-degree.pg
+++ /dev/null
@@ -1,91 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Convert from radians to degrees (5 conversions) 
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Trigonometry)
-## DBchapter(Geometric and algebraic foundations for trigonometry)
-## DBsection(Radians, converting radians & degrees)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-DOCUMENT();        # This should be the first executable line in the problem.
-
-loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "PGasu.pl",
-  "PGcourse.pl",
-  "MathObjects.pl",
-  "contextFraction.pl"
-);
-
-sub pick {
-  my ($k, @in) = @_;
-  my @out = ();
-  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
-  @out; 
-}
-
-TEXT(beginproblem());
-$showPartialCorrectAnswers = 1;
-Context("Fraction-NoDecimals");
-
-my @c = (
-  (-11,-7,-5,5,7,11)[random(0,5)], 
-  (-7, -5,-3,3,5, 7)[random(0,5)], 
-  (-8,-7,-5,-4,-2,2,4,5,7,8)[random(0,9)],
-  (-7,-5,-3,3,5,7)[random(0,5)],
-  (-5,-4,-3,3,4,5)[random(0,5)],
-);
-
-@r = (
- "\frac{$c[0]\pi}{6}",
- "\frac{$c[1]\pi}{4}",
- "\frac{$c[2]\pi}{3}",
- "\frac{$c[3]\pi}{2}", 
- "$c[4]\pi"
-);
-
-@d = (
- Compute((30*$c[0])%360),
- Compute((45*$c[1])%360),
- Compute((60*$c[2])%360),
- Compute((90*$c[3])%360),
- Compute((180*$c[4])%360)
-);
-
-foreach (0..$#c) { $s[$_] = ($c[$_] < 0) ? "" : "\phantom{x}"; }
-
-@i = pick(5,(0..4));
-
-Context()->texStrings;
-BEGIN_TEXT
-
-Convert the following $BBOLD radian $EBOLD measures to $BBOLD degrees. $EBOLD$BR
-(Write your answers as angles \(0^\circ \le \theta < 360^\circ \).)
-
-END_TEXT
-for ($j=0; $j <= $#r; $j++) {
-BEGIN_TEXT
-
-$PAR $SPACE $SPACE
-\($s[$i[$j]]$r[$i[$j]]\ \text{radians}\ = \ \) 
-\{ ans_rule(10) \} \(\text{degrees}\)
-
-END_TEXT
-}
-
-Context()->normalStrings;
-
-for ($j=0; $j <= $#d; $j++) {
-  ANS( $d[$i[$j]]->cmp() );
-}
-
-ENDDOCUMENT();        # This should be the last executable line in the problem.
-
diff --git a/Contrib/METU-NCC/MAT100/26_Trig-identities.pg b/Contrib/METU-NCC/MAT100/26_Trig-identities.pg
deleted file mode 100644
index 05892affd6..0000000000
--- a/Contrib/METU-NCC/MAT100/26_Trig-identities.pg
+++ /dev/null
@@ -1,105 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Solve trigonometric equation using trig identities 
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Trigonometry)
-## DBchapter(Analytic trigonometry)
-## DBsection(Solving trigonometric equations exactly)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-
-DOCUMENT();
-
-loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "AnswerFormatHelp.pl",
-  "PGcourse.pl"
-);
-
-TEXT(beginproblem());
-
-COMMENT("Randomly choose one of eight problems$BR (all use double angle for cos)");
-
-###################################
-#  Setup
-
-Context("Numeric");
-Context()->functions->disable("Trig");
-
-@expression = (
- " \cos(x) + \cos(2x) =  0", #1. (2cos(x)-1)(cos(x)+1) = 0 
- "3\cos(x) + \cos(2x) = -2", #2. (2cos(x)+1)(cos(x)+1) = 0
- "\cos(2x) + 2 = 3\cos(x)",  #3. (2cos(x)-1)(cos(x)-1) = 0
- "\cos(2x) = \cos(x)",       #4. (2cos(x)+1)(cos(x)-1) = 0
- "\cos(2x) + 3 = 5\cos(x)",  #5. (2cos(x)-1)(cos(x)-2) = 0
- "\cos(2x) = 1 + 3\cos(x)",  #6. (2cos(x)+1)(cos(x)-2) = 0
- "5\cos(x) + cos(2x) = -3",  #7. (2cos(x)+1)(cos(x)+2) = 0
- "3\cos(x) + cos(2x) = 1",   #8. (2cos(x)-1)(cos(x)+2) = 0
-);
-
-
-@answer = (
- List(Compute("pi"),Compute("pi/3"),Compute("5 pi/3")),   #1
- List(Compute("pi"),Compute("2 pi/3"),Compute("4 pi/3")), #2
- List(Compute("0"), Compute("pi/3"),  Compute("5 pi/3")), #3
- List(Compute("0"), Compute("2 pi/3"),Compute("4 pi/3")), #4
- List(Compute("pi/3"),Compute("5 pi/3")),                 #5
- List(Compute("2 pi/3"),Compute("4 pi/3")),               #6
- List(Compute("2 pi/3"),Compute("4 pi/3")),               #7
- List(Compute("pi/3"),Compute("5 pi/3")),                 #8
-);
-
-$i = random(0,7);
-
-
-###################################
-#  Main text
-
-Context()->texStrings;
-BEGIN_TEXT
-Use trigonometric identities to find all solutions to 
-\[ $expression[$i] \]
-for \( 0 \leq x < 2\pi \).
-$PAR
-\( x =\) \{ ans_rule(30) \}
-$PAR
-$SPACE $SPACE Write 
-solutions separated by commas.
-$BR
-$SPACE $SPACE Write angles in radians, using "${BTT}pi${ETT}" for \(\pi\).  
-$BR
-$SPACE $SPACE 
-For example
-"${BTT}2pi / 3,  5pi / 4${ETT}"
-END_TEXT
-Context()->normalStrings;
-
-
-##################################
-#  Answer evaluation
-
-$showPartialCorrectAnswers = 1;
-
-ANS($answer[$i]->cmp(
-  showHints=>0,
-  showLengthHints=>0,
-  partialCredit=>1,
-  ordered=>0,
-  removeParens=>1,
-  requireParenMatch=>0,
-  implicitList=>1,
-) );
-
-Context()->texStrings;
-
-
-;
-ENDDOCUMENT();
diff --git a/Contrib/METU-NCC/MAT100/27_Complex-roots.pg b/Contrib/METU-NCC/MAT100/27_Complex-roots.pg
deleted file mode 100644
index b9dfe71d6c..0000000000
--- a/Contrib/METU-NCC/MAT100/27_Complex-roots.pg
+++ /dev/null
@@ -1,58 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Find complex roots to equation
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Algebra)
-## DBchapter(Quadratic equations and functions)
-## DBsection(Complex roots)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-DOCUMENT();        # This should be the first executable line in the problem.
-
-loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "MathObjects.pl",
-  "PGcourse.pl"
-);
-
-TEXT(beginproblem());
-
-Context("Complex");
-Context()->variables->are(z=>'Real');
-
-$showPartialCorrectAnswers = 0;
-
-$a =  random(2,4,1) * random(-1,1,2);
-do { $b =  random(2,4,1); } until (abs($b)!=abs($a)); 
-my $c = $a**2 + $b**2;
-
-$f = Formula("z^2 - 2*$a z + $c")->reduce;
-
-Context("LimitedComplex");
-Context()->operators->undefine("^","**","sqrt");
-
-$roots = List(Complex("$a+$b i"),Complex("$a-$b i"));
-
-Context()->texStrings;
-TEXT(EV2(<<EOT));
-Find all complex solutions to the following equation.
-\[ $f = 0\] 
-Answer: \(z= \)\{ans_rule(40) \} 
-$PAR $SPACE $SPACE
-Write your answer as a list of complex numbers without using powers or roots,
-e.g. "3-4i, 5+i". 
-EOT
-Context()->normalStrings;
-
-ANS( $roots->cmp(partialCredit=>1) );
-
-ENDDOCUMENT();        # This should be the last executable line in the problem.
-
diff --git a/Contrib/METU-NCC/MAT100/3_Absolute-equality.pg b/Contrib/METU-NCC/MAT100/3_Absolute-equality.pg
deleted file mode 100644
index 01284ef56e..0000000000
--- a/Contrib/METU-NCC/MAT100/3_Absolute-equality.pg
+++ /dev/null
@@ -1,63 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Solve equality with absolute value 
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Algebra)
-## DBchapter(Absolute value expressions and functions)
-## DBsection(Solving equations with absolute values)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-DOCUMENT(); # This should be the first executable line in the problem.
-
-loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "AnswerFormatHelp.pl",
-  "PGcourse.pl"
-);
-
-######################################
-#  Setup
-
-$var = ("a","b","t","x","y")[random(0,4)];
-
-$a = random(1,7,2);
-$b = random(3,9,2);
-$c = random(1,3,2);
-
-$ans = List(Compute("($a-$b*$c)/2"),Compute("($a+$b*$c)/2"));
-
-######################################
-#  Main text
-
-TEXT(beginproblem());
-$showPartialCorrectAnswers = 0;
-
-BEGIN_TEXT
-Solve the following equality.
-\[ \left|\frac{2 $var - $a}{$b}\right| = $c \]
-$PAR
-Answer: \( $var = \)\{ ans_rule(20) \} 
-$PAR
-$SPACE $SPACE 
-Enter multiple solutions separated by commas
- e.g. "3/2 , sqrt(2)".
-END_TEXT
-
-######################################
-#  Answer
-
-ANS( $ans->cmp(partialCredit=>1));
-
-
-######################################
-
-;
-ENDDOCUMENT();
diff --git a/Contrib/METU-NCC/MAT100/3_Simplify.pg b/Contrib/METU-NCC/MAT100/3_Simplify.pg
deleted file mode 100644
index cef5a80eb8..0000000000
--- a/Contrib/METU-NCC/MAT100/3_Simplify.pg
+++ /dev/null
@@ -1,46 +0,0 @@
-## BEGIN_DESCRIPTION
-##  Simplify expression with negative fractional power 
-## END_DESCRIPTION
-##
-##############################################
-## DBsubject(Algebra)
-## DBchapter(Properties of exponents, rational exponents and radicals)
-## DBsection(Properties of rational exponents and radicals)
-## Institution(METU-NCC)
-## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
-## Level(2)
-## Language(en)
-###############################################
-
-DOCUMENT();        # This should be the first executable line in the problem.
-
-loadMacros(
-  "PGstandard.pl",
-  "PGchoicemacros.pl",
-  "MathObjects.pl",
-  "contextFraction.pl",
-  "PGcourse.pl"
-);
-
-TEXT(beginproblem());
-Context("Fraction-NoDecimals");
-Context()->operators->undefine("^","**");
-
-$showPartialCorrectAnswers = 0;
-
-$a = random(2,5);
-$a3 = $a**3;
-$ans = Fraction(1,$a**4);
-
-TEXT(EV2(<<EOT));
-Simplify the expression \($a3^{-4/3} \) without using powers or decimals.
-$PAR $SPACE $SPACE
-\($a3^{-4/3} = \) \{ans_rule(10) \}
-EOT
-
-ANS( $ans->cmp() );
-
-ENDDOCUMENT();        # This should be the last executable line in the problem.
-
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.2_Abs_value2.pg b/Contrib/METU-NCC/MAT100/Ch1/1.2_Abs_value2.pg
new file mode 100644
index 0000000000..e273e0d3f5
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.2_Abs_value2.pg
@@ -0,0 +1,99 @@
+## BEGIN_DESCRIPTION
+##  Solve equality with sum of absolute values
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Absolute value expressions and functions)
+## DBsection(Solving equations with absolute values)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Date(October 2022)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+
+DOCUMENT();
+
+loadMacros(
+"PGstandard.pl",
+"PGcourse.pl",
+"MathObjects.pl",
+"contextFraction.pl"
+);
+
+TEXT(beginproblem());
+
+COMMENT('random slopes could make answers ugly...');
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+}
+
+Context("Fraction");
+
+
+do {
+  @a = map { non_zero_random(-4,4); } (0,1); 
+  @m = map { random(1,3) } @a; 
+} until ($a[0]*$m[1] != $a[1]*$m[0]);
+
+if ($a[0]*$m[1] > $a[1]*$m[0]) { @a = @a[1,0]; @m = @m[1,0]}
+
+@crit  = (abs($m[1]*$a[0]/$m[0] - $a[1]), abs($m[0]*$a[1]/$m[1] - $a[0]));
+@crits = PGsort(sub {$_[0] < $_[1]}, @crit);
+
+do { $b = random(ceil($crits[0])+1,ceil($crits[1])+4); } 
+until ($b != $crits[1]);
+
+@x = ();
+
+if ($b > $crit[0]) {
+  push(@x, (
+   Fraction($a[0]+$a[1]-$b,
+            $m[0]+$m[1])->reduce
+  ));
+}
+if ($b == (PGsort(sub {$_[0] < $_[1]}, ($b,$crit[0],$crit[1])))[1]) {
+  push(@x, (
+   Fraction(-$a[0]+$a[1]-$b,
+            -$m[0]+$m[1])->reduce
+  ));
+}
+if ($b > $crit[1]) { 
+  push(@x, (
+   Fraction($a[0]+$a[1]+$b,
+            $m[0]+$m[1])->reduce
+  ));
+}
+
+$ans = List(@x);
+
+# if (random(0,1)==1) {@a=@a[1,0]; @m=@m[1,0];}
+
+$f = Formula("abs($m[0] x - $a[0]) + abs($m[1] x - $a[1])")->reduce;
+
+Context()->texStrings;
+BEGIN_TEXT
+
+Solve the following equation. 
+\[ \displaystyle $f = $b\]
+$PAR
+\(x= \) \{ $ans->ans_rule(10) \}
+
+
+END_TEXT
+Context()->normalStrings;
+
+ANS( $ans->cmp() );
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+       
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.3_Abs_value2.pg b/Contrib/METU-NCC/MAT100/Ch1/1.3_Abs_value2.pg
index 0e049ee72d..d9c97afc69 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.3_Abs_value2.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.3_Abs_value2.pg
@@ -42,8 +42,8 @@ do { $B = random(1,7); }
 until (($B!=$A) && ($B!=$C));
 
 
-$expr[0] = "$A\," . Formula("|x-$B|-x")->reduce->TeX .
-           "\ =\ $C\, |x|";
+$expr[0] = Formula("$A abs(x-$B)-x")->reduce->TeX .
+           "\ =\ " . Formula("$C abs(x)")->TeX;
 
 my @end = (Fraction($A*$B,($A+1)-$C),
            Fraction($A*$B,$A+$C+1));
@@ -58,8 +58,8 @@ Context()->noreduce('(-x)-y','(-x)+y');
 
 my $i = random(0,3);
 
-$expr[1] = "$A\," . Formula("|x-$B|-x")->reduce->TeX .
-    ("\ \le\ ","\ <\ ","\ \ge\ ","\ >\ ")[$i] . "$C\, |x|";
+$expr[1] = Formula("$A abs(x-$B)-x")->reduce->TeX .
+    ("\ \le\ ","\ <\ ","\ \ge\ ","\ >\ ")[$i] . Formula("$C abs(x)")->TeX;
 
 $ans[1] = 
    (Inequality("(-inf,$end[0]] U [$end[1],inf)"),
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_div.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_div.pg
index 2e4018d526..276bb39013 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_div.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_div.pg
@@ -8,10 +8,9 @@
 ## DBsection(Conversion to a + bi form)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
@@ -33,6 +32,7 @@ sub pick {
 
 TEXT(beginproblem());
 
+COMMENT("Uses LimitedComplex");
 Context("Complex");
 
 my $n = random(2010,2029); 
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_mult.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_mult.pg
index cfe2fdcc72..e6248a0da2 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_mult.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_mult.pg
@@ -8,10 +8,9 @@
 ## DBsection(Multiplication)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
@@ -69,6 +68,9 @@ $BBOLD ($index[1]) $EBOLD
 $BR 
 \(\qquad P($z) = \) \{ans_rule(10);\} 
 
+$PAR
+(Hint: This is easier if you use the answer from part $BBOLD(A)$EBOLD)
+
 END_TEXT
 
 
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-div.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-div.pg
new file mode 100644
index 0000000000..57463b3804
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-div.pg
@@ -0,0 +1,128 @@
+## BEGIN_DESCRIPTION
+##  5x complex division problems
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Complex analysis)
+## DBchapter(Arithmetic)
+## DBsection(Division)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextLimitedComplex.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("Current setup picks 5 out of 266 possible distinct division problems using complex numbers with distinct real and imaginary parts less than 5.");
+
+Context("Complex");
+
+my $number_of_problems = 5; 
+
+# basic numbers to work with
+
+my @z = (Complex(1,2),
+         Complex(1,3),
+         Complex(1,4),
+         Complex(2,3)
+);
+
+# generate new numbers by 
+#   swapping real and imaginary parts
+#   changing sign on real or imaginary parts
+#
+# total possible numbers is @z * 6
+#   consecutive pairs of numbers will give problem
+#
+# (this way we ensure problems are simple and unique)
+# 
+my @num = pick($number_of_problems*2,(0..(@z*6-1))); 
+
+my @cx_num = map { @z[$_%@z] } @num;
+
+for($i=0;$i<@num;$i++) {
+  if ($num[$i] >= 3*@z) { $cx_num[$i] = Complex(Im($cx_num[$i]),Re($cx_num[$i])); }
+
+  $num[$i] = (($num[$i] - ($num[$i]%@z))/@z) %3; 
+  if ($num[$i] == 1) { $cx_num[$i] =  conj($cx_num[$i]); }
+  if ($num[$i] == 2) { $cx_num[$i] = -conj($cx_num[$i]); }
+}
+
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = "\frac{" . $cx_num[2*$i]->TeX . "}{" . $cx_num[2*$i+1]->TeX . "}";
+  $ans[$i]      = $cx_num[2*$i] / $cx_num[2*$i+1];
+}
+
+
+# impliment poor man's alignment?
+@align = ("","\phantom{-}","\phantom{-}\phantom{-}");
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = $align[((Re($cx_num[2*$i])>0)&&(Re($cx_num[2*$i+1])>0)) ? 1 : 0]  
+                        . $question[$i];
+}
+for ($i=0;$i<@num/2;$i++) {
+  if (((abs(Im($cx_num[2*$i]))==1)&&(abs(Im($cx_num[2*$i+1]))==1))  ||
+      ((abs(Im($cx_num[2*$i]  ))==1)&&(Re($cx_num[2*$i]  )<0)&&(Re($cx_num[2*$i+1])>0)) || 
+      ((abs(Im($cx_num[2*$i+1]))==1)&&(Re($cx_num[2*$i+1])<0)&&(Re($cx_num[2*$i  ])>0))) 
+  {  $question[$i] = "\phantom{2}" . $question[$i]; }
+}
+
+
+Context("LimitedComplex");
+
+@ans = map { Compute($_) } @ans; 
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+Compute the following complex quotients:
+$PAR
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++){
+BEGIN_TEXT
+
+$BBOLD ($index[$i]) $EBOLD 
+\(\displaystyle \quad $question[$i]= \) \{ans_rule(10);\} 
+
+$PAR
+
+END_TEXT
+}
+
+BEGIN_TEXT
+You answers must be simplified to the form \(a+bi\).  No \(i\) allowed in denominators!
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-pow.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-pow.pg
new file mode 100644
index 0000000000..7142600dd8
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-pow.pg
@@ -0,0 +1,123 @@
+## BEGIN_DESCRIPTION
+##  5x complex powers problems
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Complex analysis)
+## DBchapter(Arithmetic)
+## DBsection(Multiplication)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextLimitedComplex.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+COMMENT("Current setup picks 5 out of 24 possible complex numbers with distinct real and imaginary parts less than 5. Final two are cubed.");
+
+Context("Complex");
+
+my $number_of_problems = 5; 
+
+# basic numbers to work with
+
+my @z = (Complex(1,2),
+         Complex(1,3),
+         Complex(1,4),
+         Complex(2,3)
+);
+
+# generate new numbers by 
+#   swapping real and imaginary parts
+#   changing sign on real or imaginary parts
+#
+# total possible numbers is @z * 6
+#
+# (this way we ensure problems are simple and unique)
+# 
+my @num = pick($number_of_problems,(0..(@z*6-1))); 
+
+my @cx_num = map { @z[$_%@z] } @num;
+
+# all powers are squares except for final two, which are cubes
+#  this could be modified to random powers, instead....
+my @pow = (2)x@cx_num;  @pow[$#pow]=3; @pow[$#pow-1]=3;
+
+for($i=0;$i<@num;$i++) {
+  if ($num[$i] >= 3*@z) { $cx_num[$i] = Complex(Im($cx_num[$i]),Re($cx_num[$i])); }
+
+  $num[$i] = (($num[$i] - ($num[$i]%@z))/@z) %3; 
+  if ($num[$i] == 1) { $cx_num[$i] =  conj($cx_num[$i]); }
+  if ($num[$i] == 2) { $cx_num[$i] = -conj($cx_num[$i]); }
+}
+
+for ($i=0;$i<@num;$i++) {
+  $question[$i] = "(" . $cx_num[$i]->TeX . ")^$pow[$i]";
+  $ans[$i]      = ($cx_num[$i])**$pow[$i];
+}
+
+
+# impliment poor man's alignment?
+@align = ("","\phantom{-}","\phantom{-}\phantom{-}");
+for ($i=0;$i<@num;$i++) {
+  $question[$i] = $align[((Re($cx_num[$i])>0)   ? 1 : 0)] . $question[$i];
+}
+@align = ("","\phantom{2}","\phantom{2}\phantom{2}");
+for ($i=0;$i<@num;$i++) {
+  $question[$i] = $align[((abs(Im($cx_num[$i]))==1)   ? 1 : 0)] . $question[$i];
+}
+
+
+Context("LimitedComplex");
+
+@ans = map { Compute($_) } @ans; 
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+Compute the following complex squares and cubes:
+$PAR
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++){
+BEGIN_TEXT
+
+$BBOLD ($index[$i]) $EBOLD 
+\(\quad $question[$i]= \) \{ans_rule(10);\} 
+
+$PAR
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-prod.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-prod.pg
new file mode 100644
index 0000000000..2b94d45b03
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-prod.pg
@@ -0,0 +1,122 @@
+## BEGIN_DESCRIPTION
+##  5x complex multiplication problems
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Complex analysis)
+## DBchapter(Arithmetic)
+## DBsection(Multiplication)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextLimitedComplex.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+COMMENT("Current setup picks 5 out of 266 possible distinct multiplication problems using complex numbers with distinct real and imaginary parts less than 5.");
+
+Context("Complex");
+
+my $number_of_problems = 5; 
+
+# basic numbers to work with
+
+my @z = (Complex(1,2),
+         Complex(1,3),
+         Complex(1,4),
+         Complex(2,3)
+);
+
+# generate new numbers by 
+#   swapping real and imaginary parts
+#   changing sign on real or imaginary parts
+#
+# total possible numbers is @z * 6
+#   consecutive pairs of numbers will give problem
+#
+# (this way we ensure problems are simple and unique)
+# 
+my @num = pick($number_of_problems*2,(0..(@z*6-1))); 
+
+my @cx_num = map { @z[$_%@z] } @num;
+
+for($i=0;$i<@num;$i++) {
+  if ($num[$i] >= 3*@z) { $cx_num[$i] = Complex(Im($cx_num[$i]),Re($cx_num[$i])); }
+
+  $num[$i] = (($num[$i] - ($num[$i]%@z))/@z) %3; 
+  if ($num[$i] == 1) { $cx_num[$i] =  conj($cx_num[$i]); }
+  if ($num[$i] == 2) { $cx_num[$i] = -conj($cx_num[$i]); }
+}
+
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = "(" . $cx_num[2*$i]->TeX . ")\,(" . $cx_num[2*$i+1]->TeX . ")";
+  $ans[$i]      = $cx_num[2*$i] * $cx_num[2*$i+1];
+}
+
+
+# impliment poor man's alignment?
+@align = ("","\phantom{-}","\phantom{-}\phantom{-}");
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = $align[((Re($cx_num[2*$i])>0)   ? 1 : 0) + 
+                         ((Re($cx_num[2*$i+1])>0) ? 1 : 0)] . $question[$i];
+}
+@align = ("","\phantom{2}","\phantom{2}\phantom{2}");
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = $align[((abs(Im($cx_num[2*$i]))==1)   ? 1 : 0) + 
+                         ((abs(Im($cx_num[2*$i+1]))==1) ? 1 : 0)] . $question[$i];
+}
+
+
+Context("LimitedComplex");
+
+@ans = map { Compute($_) } @ans; 
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+Compute the following complex products:
+$PAR
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++){
+BEGIN_TEXT
+
+$BBOLD ($index[$i]) $EBOLD 
+\(\quad $question[$i]= \) \{ans_rule(10);\} 
+
+$PAR
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-sum.pg b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-sum.pg
new file mode 100644
index 0000000000..4462e50ef9
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.4_C_multi-sum.pg
@@ -0,0 +1,125 @@
+## BEGIN_DESCRIPTION
+##  5x complex addition/subtraction problems
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Complex analysis)
+## DBchapter(Arithmetic)
+## DBsection(Addition/subtraction)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextLimitedComplex.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+COMMENT("Current setup picks 5 out of 266 possible distinct sum/diff problems using complex numbers with distinct real and imaginary parts less than 5.");
+
+Context("Complex");
+
+my $number_of_problems = 5; 
+
+# basic numbers to work with
+
+my @z = (Complex(1,2),
+         Complex(1,3),
+         Complex(1,4),
+         Complex(2,3)
+);
+
+# generate new numbers by 
+#   swapping real and imaginary parts
+#   changing sign on real or imaginary parts
+#
+# total possible numbers is @z * 6
+#   consecutive pairs of numbers will give problem
+#
+# (this way we ensure problems are simple and unique)
+# 
+my @num = pick($number_of_problems*2,(0..(@z*6-1))); 
+
+my @cx_num = map { @z[$_%@z] } @num;
+
+for($i=0;$i<@num;$i++) {
+  if ($num[$i] >= 3*@z) { $cx_num[$i] = Complex(Im($cx_num[$i]),Re($cx_num[$i])); }
+
+  $num[$i] = (($num[$i] - ($num[$i]%@z))/@z) %3; 
+  if ($num[$i] == 1) { $cx_num[$i] =  conj($cx_num[$i]); }
+  if ($num[$i] == 2) { $cx_num[$i] = -conj($cx_num[$i]); }
+}
+
+@sign = ("+")x(@num/2);
+@sign[(pick(ceil(@num/4),(0..(@num/2))))] = ("-")x(ceil(@num/4));
+
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = "(" . $cx_num[2*$i]->TeX . ") $sign[$i] (" . $cx_num[2*$i+1]->TeX . ")";
+  $ans[$i]      = Compute("$cx_num[2*$i] $sign[$i] $cx_num[2*$i+1]");
+}
+
+
+# impliment poor man's alignment?
+@align = ("","\phantom{-}","\phantom{-}\phantom{-}");
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = $align[((Re($cx_num[2*$i])>0)   ? 1 : 0) + 
+                         ((Re($cx_num[2*$i+1])>0) ? 1 : 0)] . $question[$i];
+}
+@align = ("","\phantom{2}","\phantom{2}\phantom{2}");
+for ($i=0;$i<@num/2;$i++) {
+  $question[$i] = $align[((abs(Im($cx_num[2*$i]))==1)   ? 1 : 0) + 
+                         ((abs(Im($cx_num[2*$i+1]))==1) ? 1 : 0)] . $question[$i];
+}
+
+
+Context("LimitedComplex");
+
+@ans = map { Compute($_) } @ans; 
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+Compute the following complex sums or differences:
+$PAR
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++){
+BEGIN_TEXT
+
+$BBOLD ($index[$i]) $EBOLD 
+\(\quad $question[$i]= \) \{ans_rule(10);\} 
+
+$PAR
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula1.pg b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula1.pg
new file mode 100644
index 0000000000..e41dd51c47
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula1.pg
@@ -0,0 +1,88 @@
+## BEGIN_DESCRIPTION
+##  Quadratic formula 
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Quadratic formula)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("Equation is x^2 + 2bx + c; does not factor in Z");
+
+Context("Numeric");
+Context()->noreduce('(-x)-y','(-x)+y');
+Context()->flags->set(
+ reduceConstants => 0,
+ reduceConstantFunctions => 0,
+);
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+# generate coefficients for quadratic x^2 + 2bx + c that
+#  does NOT factor in Z   ($d is discriminant)
+do {
+  ($b,$c) = (non_zero_random(-6,6),non_zero_random(-8,8)); 
+  $d = ($b)**2-$c; $d = ($d < 1) ? 1 : sqrt($d);
+} while ($d==int($d)) ;
+
+$expr[0] = Formula("x^2 + 2*$b x + $c")->reduce;
+
+$ans[0] = Formula("-$b");
+$ans[1] = Formula("2 sqrt(($b)^2-$c)");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+The following questions are about the solutions to 
+\[ $expr[0] = 0 \]
+$PAR
+
+$BBOLD ($index[0]) $EBOLD 
+ What is the $BBOLD average value $EBOLD of the solutions?
+$BR 
+ \(\quad \text{average value} = \) \{ans_rule(10);\}
+
+
+$PAR
+$BBOLD ($index[1]) $EBOLD 
+ What is the $BBOLD distance between $EBOLD the solutions?
+$BR 
+\(\quad \text{distance} = \) \{ans_rule(10);\} 
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+map {ANS($_->cmp())} @ans;
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula2.pg b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula2.pg
new file mode 100644
index 0000000000..f2a73176cf
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula2.pg
@@ -0,0 +1,66 @@
+## BEGIN_DESCRIPTION
+##  Quadratic formula 
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Quadratic formula)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+TEXT(beginproblem());
+
+COMMENT("Either x coeff or const is a variable.");
+
+Context("Numeric");
+Context()->variables->add(b=>"Real",c=>"Real");
+
+($b,$c) = (non_zero_random(-5,5),non_zero_random(-9,9));
+
+$expr[0] = Formula("x^2 + 2*$b x + c")->reduce;
+$expr[1] = Formula("x^2 + 2*b x + $c")->reduce;
+
+@ans    = ([Formula("-$b + sqrt(($b)^2 - c)")->reduce,
+            Formula("-$b - sqrt(($b)^2 - c)")->reduce],
+           [Formula("- b + sqrt(( b)^2 -$c)")->reduce,
+            Formula("- b - sqrt(( b)^2 -$c)")->reduce]);
+
+@word = ("larger","smaller");
+
+($i,$j) = (random(0,1),random(0,1));
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find the $BBOLD $word[$j] $EBOLD of the two solutions to 
+\[$expr[$i] = 0\]
+$PAR
+\(\quad x = \) \{ans_rule(10);\}
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS($ans[$i][$j]->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula3.pg b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula3.pg
new file mode 100644
index 0000000000..772f99557c
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.5_Quad_formula3.pg
@@ -0,0 +1,76 @@
+## BEGIN_DESCRIPTION
+##  Quadratic formula 
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Quadratic formula)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+TEXT(beginproblem());
+
+COMMENT("one coeff is number, others involve an unknonwn (only 6 possible questions)");
+
+Context("Numeric");
+Context()->variables->add(
+   a=>["Real",limits=>[.01,5]],
+   b=>["Real",limits=>[.01,5]]
+);
+
+@expr = (Formula("x^2 + 2b x - b**2"),
+         Formula("a x^2 + 2a x - 1"),
+         Formula("a x^2 + 2x - a")
+);
+
+@ans  = ([Formula(" b (-1 + sqrt(2))")->reduce,
+          Formula(" b (-1 - sqrt(2))")->reduce],
+         [Formula("-1 + sqrt(1 + 1/a)")->reduce,
+          Formula("-1 - sqrt(1 + 1/a)")->reduce],
+         [Formula("1/a*(-1 + sqrt(1+a^2))")->reduce,
+          Formula("1/a*(-1 - sqrt(1+a^2))")->reduce]
+);
+
+@word = ("larger","smaller");
+@letter = ("b","a","a");
+
+($i,$j) = (random(0,2),random(0,1));
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find the $BBOLD $word[$j] $EBOLD (assuming \($letter[$i] > 0\)) 
+of the two solutions to 
+\[$expr[$i] = 0\]
+$PAR
+\(\quad x = \) \{ans_rule(10);\}
+$BR
+
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS($ans[$i][$j]->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple1.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple1.pg
new file mode 100644
index 0000000000..9bdb9e13eb
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple1.pg
@@ -0,0 +1,81 @@
+## BEGIN_DESCRIPTION
+##  Quadratic substitution  
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Solve by factoring)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("One negative solution in (A), so only one solution to (B)");
+
+Context("Numeric");
+Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(u => "Real");
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+($a,$b) = pick(2,(1..9)); $b = -$b;
+
+$expr[0] = Formula("u^2 - ($a+$b) u + ($a*$b)")->reduce;
+$expr[1] = Formula("x - ($a+$b)sqrt(x) + ($a*$b)")->reduce;
+
+$ans[0] = List($a,$b);
+$ans[1] = List($a**2);
+
+Context()->texStrings;
+
+BEGIN_TEXT
+Solve the following linked problems.
+$PAR
+
+$BBOLD ($index[0]) $EBOLD 
+  Solve \(\displaystyle\ $expr[0]=0\) 
+$BR 
+\(\qquad u = \) \{ans_rule(5);\} 
+
+
+$PAR
+$BBOLD ($index[1]) $EBOLD 
+ Solve  \(\displaystyle\ $expr[1]=0\)
+$BR 
+\(\qquad x = \) \{ans_rule(10);\} 
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+map {ANS($_->cmp())} @ans;
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple2.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple2.pg
new file mode 100644
index 0000000000..0e614d67ff
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple2.pg
@@ -0,0 +1,81 @@
+## BEGIN_DESCRIPTION
+##  Quadratic substitution  
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Solve by factoring)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("One negative solution in (A), so only two solutions to (B)");
+
+Context("Numeric");
+Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(u => "Real");
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+($a,$b) = pick(2,(1..9)); $b = -$b;
+
+$expr[0] = Formula("u^2 - ($a+$b) u + ($a*$b)")->reduce;
+$expr[1] = Formula("x^4 - ($a+$b) x^2 + ($a*$b)")->reduce;
+
+$ans[0] = List($a,$b);
+$ans[1] = List(-sqrt($a),sqrt($a));
+
+Context()->texStrings;
+
+BEGIN_TEXT
+Find all real solutions to the following linked problems.
+$PAR
+
+$BBOLD ($index[0]) $EBOLD 
+  Solve \(\displaystyle\ $expr[0]=0\) 
+$BR 
+\(\qquad u = \) \{ans_rule(5);\} 
+
+
+$PAR
+$BBOLD ($index[1]) $EBOLD 
+ Solve  \(\displaystyle\ $expr[1]=0\)
+$BR 
+\(\qquad x = \) \{ans_rule(10);\} 
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+map {ANS($_->cmp())} @ans;
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple3.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple3.pg
new file mode 100644
index 0000000000..9a0bc12cf3
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_simple3.pg
@@ -0,0 +1,89 @@
+## BEGIN_DESCRIPTION
+##  Quadratic substitution  
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Quadratic equations and functions)
+## DBsection(Solve by factoring)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("One negative solution in (A), so only two solutions to (B)");
+
+Context("Numeric");
+Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(
+  u   => "Real",
+  x43 => ["Real",TeX=>"x^{4/3}"],
+  x23 => ["Real",TeX=>"x^{2/3}"]
+);
+
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+($a,$b) = pick(2,(1..9)); ($a,$b)=($b,$a) if ($a==1); $b = -$b;
+
+$expr[0] = Formula("u^2 - ($a+$b) u + ($a*$b)")->reduce;
+$expr[1] = Formula("x43 - ($a+$b) x23 + ($a*$b)")->reduce;
+
+Context()->flags->set(
+  reduceConstantFunctions => 0,
+);
+
+$ans[0] = List($a,$b);
+$ans[1] = List(Formula("-sqrt($a**3)"),Formula("sqrt($a**3)"));
+
+Context()->texStrings;
+
+BEGIN_TEXT
+Find all real solutions to the following linked problems.
+$PAR
+
+$BBOLD ($index[0]) $EBOLD 
+  Solve \(\displaystyle\ $expr[0]=0\) 
+$BR 
+\(\qquad u = \) \{ans_rule(5);\} 
+
+
+$PAR
+$BBOLD ($index[1]) $EBOLD 
+ Solve  \(\displaystyle\ $expr[1]=0\)
+$BR 
+\(\qquad x = \) \{ans_rule(10);\} 
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+map {ANS($_->cmp())} @ans;
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst1.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst1.pg
index e607a2cc20..315448607f 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst1.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst1.pg
@@ -35,7 +35,7 @@ COMMENT("Four real solutions");
 
 Context("Numeric");
 Context()->noreduce('(-x)-y','(-x)+y');
-
+Context()->variables->add(u => "Real");
 
 # This is a problem of type  u^2 + B u + C = 0
 #                 where u = (x^2 + b x + c)
@@ -58,7 +58,7 @@ my $u = Formula("x^2 - ($a+$b)x + $E")->reduce;
 #
 # displaying  (u)^2 + b(u) + c  with parenthesis is tricky
 #
-$expr[0] = Formula("x^2 - ($A+$B)x + $A*$B")->reduce->TeX . "=0"; 
+$expr[0] = Formula("u^2 - ($A+$B)u + $A*$B")->reduce->TeX . "=0"; 
 $expr[1] = Formula("($u)^2")->reduce->TeX .
            ( ($A+$B > 0) ? "-" : "+" ) .
            ( (abs($A+$B)==1) ? "" : abs($A+$B) ) .
@@ -79,7 +79,7 @@ $PAR
 $BBOLD ($index[0]) $EBOLD 
   Solve \(\displaystyle\ $expr[0]\) 
 $BR 
-\(\qquad x = \) \{ans_rule(5);\} 
+\(\qquad u = \) \{ans_rule(5);\} 
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst2.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst2.pg
index 3a1bfb3ef9..d32770e24e 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst2.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst2.pg
@@ -35,6 +35,8 @@ COMMENT("Only two real solutions");
 
 Context("Numeric");
 Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(u => "Real");
+
 
 # This is a problem of type  u^2 + B u + C = 0
 #                 where u = (x^2 + b x + c)    only 2 real roots
@@ -54,7 +56,7 @@ do {
 
 my $u = Formula("x^2 - ($a+$b)x + $E")->reduce;
 
-$expr[0] = Formula("x^2 - ($A+$B)x + $A*$B")->reduce->TeX . "=0"; 
+$expr[0] = Formula("u^2 - ($A+$B)u + $A*$B")->reduce->TeX . "=0"; 
 $expr[1] = Formula("($u)^2")->reduce->TeX . 
            ( ($A+$B > 0) ? "-" : "+" ) . 
            ( (abs($A+$B)==1) ? "" : abs($A+$B) ) . 
@@ -69,13 +71,13 @@ $ans[1] = List($a,$b);
 Context()->texStrings;
 
 BEGIN_TEXT
-Solve the following linked problems.
+Find all real solutions to the following linked problems.
 $PAR
 
 $BBOLD ($index[0]) $EBOLD 
   Solve \(\displaystyle\ $expr[0]\) 
 $BR 
-\(\qquad x = \) \{ans_rule(5);\} 
+\(\qquad u = \) \{ans_rule(5);\} 
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst3.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst3.pg
index 58ff291433..273b617b37 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst3.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst3.pg
@@ -35,6 +35,8 @@ COMMENT("Only two real solutions");
 
 Context("Numeric");
 Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(u => "Real");
+
 
 # This is a problem of type  u^2 + B u + C = 0
 #                 where u = sqrt(x^2 + b x + c)    only 2 real roots
@@ -44,7 +46,7 @@ my ($A,$B) = pick(2,(-6..-1,1..6));       # these will be solns
 
 my $u = Formula("x^2 - ($A+$B)x + ($A*$B + $a**2)")->reduce;
 
-$expr[0] = Formula("x^2 - ($a+$b)x + $a*$b")->reduce->TeX . "=0"; 
+$expr[0] = Formula("u^2 - ($a+$b)u + $a*$b")->reduce->TeX . "=0"; 
 $expr[1] = "(" . $u->TeX . ( ($a+$b>0) ? ")" : ")+" ) .
            Formula("-($a+$b)sqrt($u) + $a*$b")->reduce->TeX . "=0"; 
 
@@ -63,7 +65,7 @@ $PAR
 $BBOLD ($index[0]) $EBOLD 
   Solve \(\displaystyle\ $expr[0]\) 
 $BR 
-\(\qquad x = \) \{ans_rule(5);\} 
+\(\qquad u = \) \{ans_rule(5);\} 
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst4.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst4.pg
index 3783d808cf..b33d590c7f 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst4.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Quad_subst4.pg
@@ -35,6 +35,8 @@ COMMENT("Only one real solution");
 
 Context("Numeric");
 Context()->noreduce('(-x)-y','(-x)+y');
+Context()->variables->add(u => "Real");
+
 
 # This is a problem of type  u^2 + B u + C = 0
 #                 where u = sqrt(x) + A    
@@ -45,9 +47,9 @@ if ($b-$a==1) { $b=$b+1; }  # ensure that there is an integer between a&b
 
 my $A = non_zero_random($a+1,$b-1); my $B = $a+$b;  my $C = $a*$b;
 
-$expr[0] = Formula("x^2 - $B x + $C")->reduce->TeX . "=0";
+$expr[0] = Formula("u^2 - $B u + $C")->reduce->TeX . "=0";
 $expr[1] = Formula("(sqrt(x)+$A)^2")->reduce->TeX .
-           (($B<0) ? "+" : "-") . abs($B) . "(" .
+           (($B<0) ? "+" : "-") . ((abs($B)==1) ? "" : abs($B)) . "(" .
            Formula("sqrt(x)+$A")->reduce->TeX . ")" .
            (($C<0) ? "-" : "+") . abs($C) . "=0";
 
@@ -65,7 +67,7 @@ $PAR
 $BBOLD ($index[0]) $EBOLD 
   Solve \(\displaystyle\ $expr[0] \) 
 $BR 
-\(\qquad x = \) \{ans_rule(5);\} 
+\(\qquad u = \) \{ans_rule(5);\} 
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch1/1.6_Rad_subst1.pg b/Contrib/METU-NCC/MAT100/Ch1/1.6_Rad_subst1.pg
index 62c03d68c3..563ffd4e52 100644
--- a/Contrib/METU-NCC/MAT100/Ch1/1.6_Rad_subst1.pg
+++ b/Contrib/METU-NCC/MAT100/Ch1/1.6_Rad_subst1.pg
@@ -33,7 +33,7 @@ sub pick {
 TEXT(beginproblem());
 
 Context("Numeric");
-Context()->variables->are(x=>"Real",y=>"Real");
+Context()->variables->are(x=>"Real",y=>"Real",u=>"Real");
 Context()->noreduce('(-x)-y','(-x)+y');
 
 START:
@@ -49,7 +49,7 @@ my $A = $a*$b - ($B)**2;
 
 if ($a-$B < 0) { goto START; }  # ensure that $a is a solution
 
-$eqn1 = "x = " . Formula("sqrt(x-$A) + $B")->reduce->TeX;
+$eqn1 = "u = " . Formula("sqrt(u-$A) + $B")->reduce->TeX;
 
 $eqn2 = "\sqrt{x} = " .Formula("sqrt(sqrt(x)-$A)+$B")->reduce->TeX;
 
@@ -71,7 +71,7 @@ $PAR
 $BBOLD ($index[0]) $EBOLD 
  Find all real solutions to the equation \( $eqn1 \)
 $BR 
-\(\qquad x=\) \{ans_rule(10);\} 
+\(\qquad u=\) \{ans_rule(10);\} 
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts-v2.pg b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts-v2.pg
new file mode 100644
index 0000000000..950e326fcd
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts-v2.pg
@@ -0,0 +1,105 @@
+## BEGIN_DESCRIPTION
+##   Circle through three points (0,0) (A,0) (0,B)
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Linear equations and functions)
+## DBsection()
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "parserImplicitEquation.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+Context("ImplicitEquation");
+#  webwork.maa.org example suggests blanking these error messages ???
+Context()->{error}{msg}{"Can't find any solutions to your equation"} = " ";
+Context()->{error}{msg}{"Can't generate enough valid points for comparison"} = " ";
+
+my ($A,$B,$C) = map { $_ * random(-2,2,4) } pick(3,(1..5));
+
+my $a = $A/2;  
+my $b = (($C)**2 + ($B)**2 - $A*$B)/(2*$C);
+
+# $b is usually an integer... so why not ensure it?
+while ($b != ceil($b)) {  
+  ($A,$B,$C) = map { $_ * random(-2,2,4) } pick(3,(1..5));
+
+  $a = $A/2;  
+  $b = (($C)**2 + ($B)**2 - $A*$B)/(2*$C);
+}
+
+Context()->flags->set(
+  reduceConstants => 0,
+  reduceConstantFunctions => 0,
+);
+
+
+
+if (random(0,1)==0) {
+  $P = Point($A,0);  $Q = Point($B,$C);
+
+  $ans[0] = Point($a,$b);
+} else {
+  $P = Point(0,$A);  $Q = Point($C,$B);
+
+  $ans[0] = Point($b,$a);
+}
+
+($a,$b) = (abs($a),abs($b));
+
+$ans[1] = Formula("sqrt($a**2 + $b**2)");  
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+
+Find the center and radius of the circle passing through the points
+\((0,0)\), \($P\), \($Q\).
+
+$PAR
+
+Center: \{ ans_rule(25) \} $BR
+Radius: \{ ans_rule(10) \}
+
+$PAR
+
+Hint: Use the standard form of the circle equation $BR
+\(x^2 + y^2 + Ax + By = C\)
+
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts.pg b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts.pg
index 486e77ea5c..0f79d03a51 100644
--- a/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts.pg
+++ b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_3pts.pg
@@ -84,6 +84,10 @@ $PAR
 
 \{ ans_rule(25) \}
 
+$PAR
+
+Hint: Use the standard form of the circle equation $BR
+\(x^2 + y^2 + Ax + By = C\)
 
 END_TEXT
 
diff --git a/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_Rad.pg b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_Rad.pg
new file mode 100644
index 0000000000..5450c1615f
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch2/2.2_Circle_Rad.pg
@@ -0,0 +1,79 @@
+## BEGIN_DESCRIPTION
+##  Find coefficient in standard form for given radius
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Cartesian coordinate system)
+## DBsection(Circles)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+Context("Numeric");
+Context()->variables->add(A=>'Real',y=>'Real');
+Context()->flags->set(reduceConstantFunctions=>0);
+Context()->noreduce('(-x)-y','(-x)+y');
+
+@c =  pick(3,(1..5));  #  center and radius
+
+$r = $c[2];  $c[2] = ($c[2])**2 - ($c[0])**2 - ($c[1])**2;  
+
+@c[(0,1)] = map { $_*2*random(-1,1) } @c[(0,1)];
+
+my $i = random(0,1);
+
+$ans[0] = List(Real($c[$i]), Real(-$c[$i]));
+$c[$i] = Formula("A");
+
+$circle = Formula("x^2 + y^2 + $c[0] x + $c[1] y")->reduce->TeX . " = $c[2]";
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+ Find all values of \(A\) so that the circle \( $circle \) has radius \($r\). 
+  
+$BR 
+\(\qquad A=\) \{ans_rule(25);\} 
+
+
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+#ANS( essay_cmp() );
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_paral-v2.pg b/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_paral-v2.pg
new file mode 100644
index 0000000000..e11221d347
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_paral-v2.pg
@@ -0,0 +1,76 @@
+## BEGIN_DESCRIPTION
+##  Linked questions -- line equation and intercepts
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Linear equations and functions)
+## DBsection(Equations of lines: slope-intercept form)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextFraction.pl",
+  "parserImplicitPlane.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+Context("Fraction");
+Context()->variables->are(x=>"Real",y=>"Real");
+
+($a,$b) = map {$_ * random(-1,1,2)} pick(2,1..5); 
+
+my ($dx,$dy) = map {$_ * random(-1,1,2)} pick(2,1..5); 
+if (($dx<0)&&($dy<0)) {$dx = -$dx;}
+my $m = Fraction($dy,$dx);  
+my $d = non_zero_random(-5,5);
+
+$parallel = Formula("$dy x - $dx y")->reduce->TeX . " = $d";
+
+$ans[0] = Formula("$m (x-$a) + $b")->reduce;
+
+Context("ImplicitPlane");
+Context()->variables->are(x=>"Real",y=>"Real");
+
+@ans = map { ImplicitPlane("y=$_") } @ans;
+
+Context()->texStrings;
+BEGIN_TEXT
+Write an equation of the line that passes through \(($a,$b)\) and is
+parallel to the line \($parallel\). 
+$PAR
+\(\qquad \) \{ans_rule(10);\} 
+
+
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_perp-v2.pg b/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_perp-v2.pg
new file mode 100644
index 0000000000..69e73289fc
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch2/2.3_Line_perp-v2.pg
@@ -0,0 +1,76 @@
+## BEGIN_DESCRIPTION
+##  Linked questions -- line equation and intercepts
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Linear equations and functions)
+## DBsection(Equations of lines: slope-intercept form)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextFraction.pl",
+  "parserImplicitPlane.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+Context("Fraction");
+Context()->variables->are(x=>"Real",y=>"Real");
+
+($a,$b) = map {$_ * random(-1,1,2)} pick(2,1..5); 
+
+my ($dx,$dy) = map {$_ * random(-1,1,2)} pick(2,1..5); 
+if (($dx<0)&&($dy<0)) { $dx = -$dx; }
+my $m = Fraction($dy,$dx);  
+my $d = non_zero_random(-5,5);
+
+$perp = Formula("$dx x + $dy y")->reduce->TeX . " = $d";
+
+$ans[0] = Formula("$m (x-$a) + $b")->reduce;
+
+Context("ImplicitPlane");
+Context()->variables->are(x=>"Real",y=>"Real");
+
+@ans = map { ImplicitPlane("y=$_") } @ans;
+
+Context()->texStrings;
+BEGIN_TEXT
+Write an equation of the line that passes through \(($a,$b)\) and is
+perpendicular to the line \($perp\). 
+$PAR
+\(\qquad \) \{ans_rule(10);\} 
+
+
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch3/3.3_Transf_Match.pg b/Contrib/METU-NCC/MAT100/Ch3/3.3_Transf_Match.pg
index e45523a4d1..cf321d38a7 100644
--- a/Contrib/METU-NCC/MAT100/Ch3/3.3_Transf_Match.pg
+++ b/Contrib/METU-NCC/MAT100/Ch3/3.3_Transf_Match.pg
@@ -8,8 +8,6 @@
 ## DBsection(Three or more transformations)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(0)
-## Static(0)
 ## Level(2)
 ## Language(en)
 ###############################################
@@ -20,7 +18,6 @@ DOCUMENT();        # This should be the first executable line in the problem.
 loadMacros(
   "PGstandard.pl",
   "parserPopUp.pl",
-  "PGcourse.pl"
 );
 
 sub pick {
diff --git a/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table1.pg b/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table1.pg
index a2d7758eed..e539d4f209 100644
--- a/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table1.pg
+++ b/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table1.pg
@@ -19,10 +19,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "niceTables.pl",
-  "PGcourse.pl",
+"PGstandard.pl",
+"PGcourse.pl",
+"MathObjects.pl",
+"niceTables.pl",
 );
 
 sub pick {
diff --git a/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table2.pg b/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table2.pg
index c7fca139db..aafb2dd8ad 100644
--- a/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table2.pg
+++ b/Contrib/METU-NCC/MAT100/Ch3/3.5_Comp_Table2.pg
@@ -19,10 +19,10 @@
 DOCUMENT();
 
 loadMacros(
-  "PGstandard.pl",
-  "MathObjects.pl",
-  "niceTables.pl",
-  "PGcourse.pl",
+"PGstandard.pl",
+"PGcourse.pl",
+"MathObjects.pl",
+"niceTables.pl",
 );
 
 sub pick {
diff --git a/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad.pg b/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad.pg
index 3f01076a0b..f24b1fba05 100644
--- a/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad.pg
+++ b/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad.pg
@@ -8,10 +8,9 @@
 ## DBsection(Finding the inverse function)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
@@ -19,8 +18,8 @@ DOCUMENT();        # This should be the first executable line in the problem.
 
 loadMacros(
   "PGstandard.pl",
-  "MathObjects.pl",
   "PGcourse.pl",
+  "MathObjects.pl",
 );
 
 sub pick {
diff --git a/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad_Restricted.pg b/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad_Restricted.pg
index 848a6994b7..3b5e7e822f 100644
--- a/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad_Restricted.pg
+++ b/Contrib/METU-NCC/MAT100/Ch3/3.6_Inv_Quad_Restricted.pg
@@ -8,10 +8,9 @@
 ## DBsection(Finding the inverse function)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
@@ -19,9 +18,9 @@ DOCUMENT();        # This should be the first executable line in the problem.
 
 loadMacros(
   "PGstandard.pl",
+  "PGcourse.pl",
   "MathObjects.pl",
   "contextInequalities.pl",
-  "PGcourse.pl",
 );
 
 sub pick {
diff --git a/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_1.pg b/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_1.pg
index 9eaf2c0fe4..53c4b5d069 100644
--- a/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_1.pg
+++ b/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_1.pg
@@ -8,10 +8,9 @@
 ## DBsection(Zeros and multiplicities)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
diff --git a/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_2.pg b/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_2.pg
index 8c34e6b440..5d55342968 100644
--- a/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_2.pg
+++ b/Contrib/METU-NCC/MAT100/Ch4/4.1_Find_poly_2.pg
@@ -8,10 +8,9 @@
 ## DBsection(Zeros and multiplicities)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
diff --git a/Contrib/METU-NCC/MAT100/Ch4/4.3_Find_poly_C.pg b/Contrib/METU-NCC/MAT100/Ch4/4.3_Find_poly_C.pg
index 2fd9778f96..4e663d969f 100644
--- a/Contrib/METU-NCC/MAT100/Ch4/4.3_Find_poly_C.pg
+++ b/Contrib/METU-NCC/MAT100/Ch4/4.3_Find_poly_C.pg
@@ -8,10 +8,9 @@
 ## DBsection(Zeros and multiplicities)
 ## Institution(METU-NCC)
 ## Author(Benjamin Walter)
-## MO(1)
-## Static(0)
 ## Level(2)
 ## Language(en)
+## MO(1)
 ###############################################
 
 
diff --git a/Contrib/METU-NCC/MAT100/Ch5/5.5_Exp_Log_Eqns.pg b/Contrib/METU-NCC/MAT100/Ch5/5.5_Exp_Log_Eqns.pg
index 01903d8839..6d87c5fcd3 100644
--- a/Contrib/METU-NCC/MAT100/Ch5/5.5_Exp_Log_Eqns.pg
+++ b/Contrib/METU-NCC/MAT100/Ch5/5.5_Exp_Log_Eqns.pg
@@ -91,6 +91,8 @@ $BBOLD ($index[0]) $EBOLD
   Solve \(\displaystyle\ $expr[0]\) 
 $PAR 
 \(\qquad x=\) \{ans_rule(20);\} 
+$PAR
+$SPACE $SPACE $BITALIC (You may need to change base, writing your answer using \(\ln\), in order for webwork to compute correctly.)$EITALIC
 
 
 $PAR
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_1.pg
new file mode 100644
index 0000000000..312d9c6503
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_1.pg
@@ -0,0 +1,103 @@
+## BEGIN_DESCRIPTION
+##  Equivalent phase shifts
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Trigonometric functions)
+## DBsection(Sine & cosine functions - definitions, graphs, & properties)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextFraction.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  return $in[random(0,$#in)] if ($k==1);
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+# Euclidean algorithm (from perlmonks.org)
+sub reduce {
+  ($x,$y) = @_; 
+  ($x,$y) = ($y%$x,$x) while $x;
+  map $_/$y,@_
+}
+
+TEXT(beginproblem());
+
+COMMENT("equivalent phase shifts");
+
+
+Context("Fraction");
+Context()->variables->are(x=>"Real");
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+
+my $b = random(5,7);
+my $a = random(1,$b-1);
+($a,$b) = reduce($a,$b);
+
+my $phi = Formula("$a pi/$b")->reduce; 
+
+$expr = Formula("sin(x+$phi)");
+
+@q = (
+  " \sin\Bigl(x-",
+  " \cos\Bigl(x+",
+  "-\sin\Bigl(x+",
+  "-\cos\Bigl(x+",
+);
+
+@ans = (
+  Formula("2 pi - $phi")->reduce, 
+  Formula("$phi - pi/2")->reduce, 
+  Formula("$phi + pi")->reduce, 
+  Formula("$phi + pi/2")->reduce, 
+);
+
+$ans[1] = Formula("$phi + 3 pi/2")->reduce if ($ans[1] < 0);
+
+@index = ("a","b","c","d","e","f","g");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Fill in the angle between \(0\) and \(2\pi\) making expressions equal.
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++) {
+BEGIN_TEXT
+
+$PAR
+($index[$i]) \(\quad $expr = $q[$i]\) \{ans_rule(10);\} \(\Bigr)\)
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_2.pg b/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_2.pg
new file mode 100644
index 0000000000..b21b965e61
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.2_Equiv_2.pg
@@ -0,0 +1,103 @@
+## BEGIN_DESCRIPTION
+##  Equivalent phase shifts
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Trigonometric functions)
+## DBsection(Sine & cosine functions - definitions, graphs, & properties)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextFraction.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  return $in[random(0,$#in)] if ($k==1);
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+# Euclidean algorithm (from perlmonks.org)
+sub reduce {
+  ($x,$y) = @_; 
+  ($x,$y) = ($y%$x,$x) while $x;
+  map $_/$y,@_
+}
+
+TEXT(beginproblem());
+
+COMMENT("equivalent phase shifts");
+
+
+Context("Fraction");
+Context()->variables->are(x=>"Real");
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+
+my $b = random(5,7);
+my $a = random(1,$b-1);
+($a,$b) = reduce($a,$b);
+
+my $phi = Formula("$a pi/$b")->reduce; 
+
+$expr = Formula("cos(x+$phi)");
+
+@q = (
+  " \cos\Bigl(x-",
+  " \sin\Bigl(x+",
+  "-\cos\Bigl(x+",
+  "-\sin\Bigl(x+",
+);
+
+@ans = (
+  Formula("2 pi - $phi")->reduce, 
+  Formula("$phi + pi/2")->reduce, 
+  Formula("$phi + pi")->reduce, 
+  Formula("$phi - pi/2")->reduce, 
+);
+
+$ans[3] = Formula("$phi + 3 pi/2")->reduce if ($ans[3] < 0);
+
+@index = ("a","b","c","d","e","f","g");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Fill in the angle between \(0\) and \(2\pi\) making expressions equal.
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++) {
+BEGIN_TEXT
+
+$PAR
+($index[$i]) \(\quad $expr = $q[$i]\) \{ans_rule(10);\} \(\Bigr)\)
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.4_Mixed_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.4_Mixed_1.pg
new file mode 100644
index 0000000000..8958dcf47e
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.4_Mixed_1.pg
@@ -0,0 +1,127 @@
+## BEGIN_DESCRIPTION
+##  Product to Sum & Sum to Product Formula
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Product-to-sum & sum-to-product formulas)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("product-sum and sum-product formulas");
+
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+# code below modified from  
+# /Library/LoyolaChicago/Precalc/Chap7Sec3/Connally3-7-3-01-Angle-sum-formulas.pg
+Context()->functions->remove("sin","cos");
+package NewFunc;
+# this next line makes the function a
+# function from reals to reals
+our @ISA = qw(Parser::Function::numeric);
+sub sin {
+  shift; my $x = shift;
+  return $x - $x**3 / 6;
+}
+sub cos {
+  shift; my $x = shift;
+  return 1 - $x**2 / 2;
+}
+package main;
+# Make it work on formulas as well as numbers
+#sub sin {Parser::Function->call('sin',@_)} # if uncommented, this line will generate error messages
+#  Add the new functions to the Context
+Context()->functions->add( 
+  sin => {class => 'NewFunc', TeX => '\sin'}, 
+  cos => {class => 'NewFunc', TeX => '\cos'}
+);
+
+($a,$b) = pick(2,(1..9));
+
+ 
+@ans =(
+   Formula("2 sin(($a+$b)/2 x) cos(abs($a-$b)/2 x)"),
+   Formula("2 sin(($a-$b)/2 x) cos(abs($a+$b)/2 x)"),
+   Formula("2 cos(($a+$b)/2 x) cos(abs($a-$b)/2 x)"),
+   Formula("2 sin(($a+$b)/2 x) sin(($b-$a)/2 x)"),
+   Formula("1/2(sin(($a+$b) x) + sin(($a-$b) x))"), 
+   Formula("1/2(sin(($a+$b) x) + sin(($b-$a) x))"), 
+   Formula("1/2(cos(($a+$b) x) + cos(abs($a-$b) x))"), 
+   Formula("1/2(cos(abs($a-$b) x) - cos(($a+$b) x))"),
+);
+
+$a = "" if ($a==1); 
+$b = "" if ($b==1); 
+
+@q = (
+   Formula("sin($a x) + sin($b x)"), 
+   Formula("sin($a x) - sin($b x)"), 
+   Formula("cos($a x) + cos($b x)"), 
+   Formula("cos($a x) - cos($b x)"), 
+   Formula("sin($a x) cos($b x)"),
+   Formula("cos($a x) sin($b x)"),
+   Formula("cos($a x) cos($b x)"),
+   Formula("sin($a x) sin($b x)"),
+);
+my @p = (random(0,1),random(2,3)); 
+   @p = (@p, map($_+4,@p));
+   @p = pick(4,@p); 
+
+@q   = @q[@p];
+@ans = @ans[@p];
+
+@index = ("a","b","c","d","e","f","g");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Convert between products and sums.
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++) {
+BEGIN_TEXT
+
+$PAR
+($index[$i]) \(\quad $q[$i] = \) \{ans_rule(10);\}
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.4_Prod-Sum_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.4_Prod-Sum_1.pg
new file mode 100644
index 0000000000..083e2bd52b
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.4_Prod-Sum_1.pg
@@ -0,0 +1,115 @@
+## BEGIN_DESCRIPTION
+##  Product to Sum Formula
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Product-to-sum & sum-to-product formulas)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("product to sum formula");
+
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+# code below modified from  
+# /Library/LoyolaChicago/Precalc/Chap7Sec3/Connally3-7-3-01-Angle-sum-formulas.pg
+Context()->functions->remove("sin","cos");
+package NewFunc;
+# this next line makes the function a
+# function from reals to reals
+our @ISA = qw(Parser::Function::numeric);
+sub sin {
+  shift; my $x = shift;
+  return $x - $x**3 / 6;
+}
+sub cos {
+  shift; my $x = shift;
+  return 1 - $x**2 / 2;
+}
+package main;
+# Make it work on formulas as well as numbers
+#sub sin {Parser::Function->call('sin',@_)} # if uncommented, this line will generate error messages
+#  Add the new functions to the Context
+Context()->functions->add( 
+  sin => {class => 'NewFunc', TeX => '\sin'}, 
+  cos => {class => 'NewFunc', TeX => '\cos'}
+);
+
+($a,$b) = pick(2,(1..9));
+
+my @sum = (
+  Formula("1/2(sin(($a+$b) x) + sin(($a-$b) x))"), 
+  Formula("1/2(sin(($a+$b) x) + sin(($b-$a) x))"), 
+  Formula("1/2(cos(($a+$b) x) + cos(abs($a-$b) x))"), 
+  Formula("1/2(cos(abs($a-$b) x) - cos(($a+$b) x))")
+); 
+$a = "" if ($a==1);
+$b = "" if ($b==1);
+my @prod =(
+  Formula("sin($a x) cos($b x)"),
+  Formula("cos($a x) sin($b x)"),
+  Formula("cos($a x) cos($b x)"),
+  Formula("sin($a x) sin($b x)")
+);
+
+my @p = pick(4,(0..3));
+
+@q   = @prod[@p];
+@ans = @sum[@p];
+
+@index = ("a","b","c","d","e","f","g");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Convert products to sums.
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++) {
+BEGIN_TEXT
+
+$PAR
+($index[$i]) \(\quad $q[$i] = \) \{ans_rule(10);\}
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.4_Sum-Prod_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.4_Sum-Prod_1.pg
new file mode 100644
index 0000000000..8b2a5cc07c
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.4_Sum-Prod_1.pg
@@ -0,0 +1,113 @@
+## BEGIN_DESCRIPTION
+##  Sum to Product Formula
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Product-to-sum & sum-to-product formulas)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("sum to product formula");
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+# code below modified from  
+# /Library/LoyolaChicago/Precalc/Chap7Sec3/Connally3-7-3-01-Angle-sum-formulas.pg
+Context()->functions->remove("sin","cos");
+package NewFunc;
+# this next line makes the function a
+# function from reals to reals
+our @ISA = qw(Parser::Function::numeric);
+sub sin {
+  shift; my $x = shift;
+  return $x - $x**3 / 6;
+}
+sub cos {
+  shift; my $x = shift;
+  return 1 - $x**2 / 2;
+}
+package main;
+# Make it work on formulas as well as numbers
+#sub sin {Parser::Function->call('sin',@_)} # if uncommented, this line will generate error messages
+#  Add the new functions to the Context
+Context()->functions->add( 
+  sin => {class => 'NewFunc', TeX => '\sin'}, 
+  cos => {class => 'NewFunc', TeX => '\cos'}
+);
+
+($a,$b) = pick(2,(1..9));
+
+my @prod =(
+   Formula("2 sin(($a+$b)/2 x) cos(abs($a-$b)/2 x)"),
+   Formula("2 sin(($a-$b)/2 x) cos(abs($a+$b)/2 x)"),
+   Formula("2 cos(($a+$b)/2 x) cos(abs($a-$b)/2 x)"),
+   Formula("2 sin(($a+$b)/2 x) sin(($b-$a)/2 x)")
+);
+$a = "" if ($a==1);
+$b = "" if ($b==1);
+my @sum = (
+   Formula("sin($a x) + sin($b x)"), 
+   Formula("sin($a x) - sin($b x)"), 
+   Formula("cos($a x) + cos($b x)"), 
+   Formula("cos($a x) - cos($b x)")
+);
+my @p = pick(4,(0..3));
+
+@q   = @sum[@p];
+@ans = @prod[@p];
+
+@index = ("a","b","c","d","e","f","g");
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Convert sums to products.
+
+END_TEXT
+for($i=0;$i<=$#ans;$i++) {
+BEGIN_TEXT
+
+$PAR
+($index[$i]) \(\quad $q[$i] = \) \{ans_rule(10);\}
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_Trig_combo.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_Trig_combo.pg
index b88a267c39..1cbbd31201 100644
--- a/Contrib/METU-NCC/MAT100/Ch7/7.5_Trig_combo.pg
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_Trig_combo.pg
@@ -41,7 +41,7 @@ Context()->noreduce('(-x)-y');
 
 my @trig = ("\sin","\cos"); my $t = random(0,1);
 my @angle;                  
-my ($i,$j) = (random(0,2),random(-1,1));
+my ($i,$j) = (random(0,2),random(-1,1,2));
 
 $angle[0] = $j*(30,45,60)[$i]-180;
 $expr[0] = "$trig[$t]\bigl( $angle[0]^\circ \bigr)";
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_1.pg
new file mode 100644
index 0000000000..7aa7921c59
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_1.pg
@@ -0,0 +1,80 @@
+## BEGIN_DESCRIPTION
+##  trig eqn with cos2x
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Solving trigonometric equations exactly)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+
+TEXT(beginproblem());
+
+COMMENT("one of eight different problems, three solutions");
+
+Context("Numeric");
+#Context()->constants->remove(pi);
+Context()->variables->add(pi=>['Real',TeX=>"\pi"]);
+#Context()->flags->set(
+#   reduceConstants => 0,
+#   reduceConstantFunctions => 0,
+#);
+
+my ($a,$b)=(random(0,1),random(0,1));
+
+$i = random(0,1);
+
+my ($c,$d) = ((-1)**($a)+2*(-1)**($b),(-1)**($a+$b)+1);
+
+if ($i==0) {
+  $f   = Formula("cos(2x) + $c cos(x) + $d")->reduce;
+  $ans = List((Formula("2 pi/3"), Formula("  pi/3"))[$a],
+              (Formula("4 pi/3"), Formula("5 pi/3"))[$a],  
+              (Formula("pi"), Formula("0"))[$b]);
+} else {
+  $f   = Formula("cos(2x) - $c sin(x) - $d")->reduce;
+  $ans = List((Formula(" 7 pi/6"), Formula("  pi/6"))[$a],
+              (Formula("11 pi/6"), Formula("5 pi/6"))[$a], 
+              (Formula(" 3 pi/2"), Formula("  pi/2"))[$b]);
+}
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find all solutions \(x\in [0,2\pi)\).
+\[ $f = 0 \]
+
+$PAR
+
+\(\quad x = \) \{ ans_rule(10); \}
+
+$PAR
+Note: your answer must be written using "pi" for \(\pi\).
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS(List($ans)->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_2.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_2.pg
new file mode 100644
index 0000000000..294efc8b07
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_2.pg
@@ -0,0 +1,82 @@
+## BEGIN_DESCRIPTION
+##  trig eqn with cos2x
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Solving trigonometric equations exactly)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+
+TEXT(beginproblem());
+
+COMMENT("one of four different problems");
+
+Context("Numeric");
+#Context()->constants->remove(pi);
+Context()->variables->add(pi=>['Real',TeX=>"\pi"]);
+#Context()->flags->set(
+#   reduceConstants => 0,
+#   reduceConstantFunctions => 0,
+#);
+
+my $a = random(0,1); 
+
+$i = random(0,1);
+
+my $c = ($a+1)*(-1)**($i+$a);
+
+if ($i==0) {
+  $f   = Formula("$c cos^2(x)")->reduce;
+  $ans = (
+    List(Formula("0"),Formula("pi")),
+    List(Formula("pi/3"),Formula("2 pi/3"),Formula("4 pi/3"),Formula("5 pi/3")), 
+  )[$a];
+} else {
+  $f   = Formula("$c sin^2(x)")->reduce;
+  $ans = (
+    List(Formula("pi/2"),Formula("3 pi/2")),
+    List(Formula("pi/6"),Formula("5 pi/6"),Formula("7 pi/6"),Formula("11 pi/6")), 
+  )[$a];
+}
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find all solutions \(x\in [0,2\pi)\).
+\[ \cos(2x) = $f \]
+
+$PAR
+
+\(\quad x = \) \{ ans_rule(10); \}
+
+$PAR
+Note: your answer must be written using "pi" for \(\pi\).
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS(List($ans)->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_3.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_3.pg
new file mode 100644
index 0000000000..44f167b2f1
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_cos2x_3.pg
@@ -0,0 +1,112 @@
+## BEGIN_DESCRIPTION
+##  trig eqn with cos2x
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Solving trigonometric equations exactly)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+
+sub pick {
+  my ($k, @in) = @_;
+  return $in[random(0,$#in)] if ($k==1);
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+};
+
+
+TEXT(beginproblem());
+
+COMMENT("factors: cos x=1 or cos x=1/2 and cos x > 1; or equivalent with sin");
+
+Context("Numeric");
+#Context()->constants->remove(pi);
+Context()->variables->add(pi=>['Real',TeX=>"\pi"]);
+#Context()->flags->set(
+#   reduceConstants => 0,
+#   reduceConstantFunctions => 0,
+#);
+
+my ($a,$b) = PGsort ( sub {$_[0] < $_[1]} , pick(2, (1..6)) );
+my ($s,$t) = (random(0,1),random(0,1));      # signs of solutions
+
+
+
+if (random(0,1)==0) {  # cos or sin = 1/2
+  my ($c,$d) = ($a*(-1)**$s + 2*$b*(-1)**$t, $a + $b*(-1)**($s+$t));
+
+  if (random(0,1)==0) { # cos x = 1/2 
+    $f   = Formula("$a cos(2x) + $c cos(x) + $d")->reduce;
+
+    $ans = (List(Formula("2 pi/3"),Formula("4 pi/3")),
+            List(Formula("  pi/3"),Formula("5 pi/3")))[$s];
+
+  } else {              # sin x = 1/2
+    $f   = Formula("$a cos(2x) - $c sin(x) - $d")->reduce;
+
+    $ans = (List(Formula("7 pi/6"),Formula("11 pi/6")),
+            List(Formula("  pi/6"),Formula(" 5 pi/6")))[$s];
+  }
+
+} else {               # cos or sin = 1
+  ($a,$b)=($a+1,$b+1) if (($a%2)!=0);
+
+  my ($c,$d) = ($a*(-1)**$s + $b*(-1)**$t, $a/2 + $b*(-1)**($s+$t));
+
+  if (random(0,1)==0) { # cos x = 1
+    $f   = Formula("$a/2 cos(2x) + $c cos(x) + $d")->reduce;
+
+    $ans = (List(Formula("pi")),
+            List(Formula("0")))[$s];
+
+  } else {              # sin x = 1
+    $f   = Formula("$a/2 cos(2x) - $c sin(x) - $d")->reduce;
+
+    $ans = (List(Formula("3 pi/2")),
+            List(Formula("  pi/2")))[$s];
+
+ }
+}
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find all solutions \(x\in [0,2\pi)\).
+\[ $f = 0 \]
+
+$PAR
+
+\(\quad x = \) \{ ans_rule(10); \}
+
+$PAR
+Note: your answer must be written using "pi" for \(\pi\).
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS(List($ans)->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_1.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_1.pg
new file mode 100644
index 0000000000..659f0b76d0
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_1.pg
@@ -0,0 +1,107 @@
+## BEGIN_DESCRIPTION
+##  trig eqn with sin2x
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Solving trigonometric equations exactly)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+
+sub pick {
+  my ($k, @in) = @_;
+  return $in[random(0,$#in)] if ($k==1);
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+};
+
+
+TEXT(beginproblem());
+
+COMMENT("8 possibilities: sin 2x +- trig^n x = 0");
+
+Context("Numeric");
+#Context()->constants->remove(pi);
+Context()->variables->add(pi=>['Real',TeX=>"\pi"]);
+#Context()->flags->set(
+#   reduceConstants => 0,
+#   reduceConstantFunctions => 0,
+#);
+
+my $s = random(0,1);    # signs of solutions
+
+
+if (random(0,1)==0) {   # cos
+
+  if (random(0,1)==0) { # n = 1
+    $f   = ($s==0) ? "\sin(2x) + \cos(x) = 0" : "\sin(2x) = \cos(x)";
+
+    $ans = ($s==0) ? List(Formula("7 pi/6"),Formula("11 pi/6")) :
+                     List(Formula("  pi/6"),Formula(" 5 pi/6"));
+
+  } else {              # n = 2 
+    $f   = ($s==0) ? "\sin(2x) + 2\cos^2(x) = 0" : "\sin(2x) = 2\cos^2(x)";
+
+    $ans = ($s==0) ? List(Formula("3 pi/4"),Formula("7 pi/4")) :
+                     List(Formula("  pi/4"),Formula("5 pi/4"));
+  }
+  $ans = List($ans->value,Formula("pi/2"),Formula("3 pi/2")); # include cos x = 0
+
+} else {               # sin 
+
+  if (random(0,1)==0) { # n = 1
+    $f   = ($s==0) ? "\sin(2x) + \sin(x) = 0" : "\sin(2x) = \sin(x)";
+
+    $ans = ($s==0) ? List(Formula("2 pi/3"),Formula("4 pi/3")) :
+                     List(Formula("  pi/3"),Formula("5 pi/3"));
+ 
+  } else {              # n = 2
+    $f   = ($s==0) ? "\sin(2x) + 2\sin^2(x) = 0" : "\sin(2x) = 2\sin^2(x)";
+
+    $ans = ($s==0) ? List(Formula("3 pi/4"),Formula("7 pi/4")) :
+                     List(Formula("  pi/4"),Formula("5 pi/4"));
+ }
+  $ans = List($ans->value,Formula("0"),Formula("pi"));     # include sin x = 0
+}
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find all solutions \(x\in [0,2\pi)\).
+\[ $f  \]
+
+$PAR
+
+\(\quad x = \) \{ ans_rule(10); \}
+
+$PAR
+Note: your answer must be written using "pi" for \(\pi\).
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS(List($ans)->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_2.pg b/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_2.pg
new file mode 100644
index 0000000000..a13b5d1dab
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch7/7.5_sin2x_2.pg
@@ -0,0 +1,127 @@
+## BEGIN_DESCRIPTION
+##  trig eqn with sin2x
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Analytic trigonometry)
+## DBsection(Solving trigonometric equations exactly)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+
+sub pick {
+  my ($k, @in) = @_;
+  return $in[random(0,$#in)] if ($k==1);
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+};
+
+
+TEXT(beginproblem());
+
+COMMENT("16 possibilities: sin x and cos x = +-1 or = +-1/2");
+
+Context("Numeric");
+#Context()->constants->remove(pi);
+Context()->variables->add(pi=>['Real',TeX=>"\pi"]);
+#Context()->flags->set(
+#   reduceConstants => 0,
+#   reduceConstantFunctions => 0,
+#);
+
+my ($s,$t) = (random(0,1),random(0,1));    # signs of solutions
+
+($lhs,$rhs) = (Formula("sin(2x)"),Formula("0"));
+
+$ans = List("");
+
+if (random(0,1)==0) {   # 2 sin x = +-1 
+
+  $ans = ($s==0) ? List(Formula("7 pi/6"),Formula("11 pi/6")) :
+                   List(Formula("  pi/6"),Formula(" 5 pi/6"));
+
+  if (random(0,1)==0) { # 2 cos x = +-1
+    $lhs *= 2;
+
+    if ($s==0) { $lhs += Formula("2 cos(x)"); } else { $rhs += Formula("2 cos(x)"); }
+
+    $ans = List($ans->value, 
+        ($t==0) ? (Formula("2 pi/3"),Formula("4 pi/3")) :
+                  (Formula("  pi/3"),Formula("5 pi/3")));
+
+
+  } else {              # cos x = +-1
+    if ($s==0) { $lhs += Formula("  cos(x)"); } else { $rhs += Formula("  cos(x)"); }
+
+    $ans = List($ans->value, 
+        ($t==0) ? Formula("pi") :
+                  Formula("0"));
+  }
+  if ($t==0) { $lhs += Formula("2 sin(x)"); } else { $rhs += Formula("2 sin(x)"); }
+  if (($s+$t)%2==0) { $lhs += Formula("1"); } else { $rhs += Formula("1");        }
+
+} else {               # sin x = +-1
+  $ans = ($s==0) ? List(Formula("3 pi/2")) :
+                   List(Formula("  pi/2"));
+
+  if (random(0,1)==0) { # 2 cos x = +-1
+    if ($t==0) { $lhs += Formula("  sin(x)"); } else { $rhs += Formula("  sin(x)"); }
+    if (($s+$t)%2==0) { $lhs += Formula("1"); } else { $rhs += Formula("1");        }
+
+    $ans = List($ans->value, 
+        ($t==0) ? (Formula("2 pi/3"),Formula("4 pi/3")) :
+                  (Formula("  pi/3"),Formula("5 pi/3")));
+ 
+  } else {              # cos x = +-1
+    if ($t==0) { $lhs += Formula("2 sin(x)"); } else { $rhs += Formula("2 sin(x)"); }
+    if (($s+$t)%2==0) { $lhs += Formula("2"); } else { $rhs += Formula("2");        }
+
+    $ans = List($ans->value, 
+        ($t==0) ? Formula("pi") :
+                  Formula("0"));
+  }
+  if ($s==0) { $lhs += Formula("2 cos(x)"); } else { $rhs += Formula("2 cos(x)"); }
+}
+
+$lhs = $lhs->reduce; $rhs = $rhs->reduce;
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find all solutions \(x\in [0,2\pi)\).
+\[ $lhs = $rhs  \]
+
+$PAR
+
+\(\quad x = \) \{ ans_rule(10); \}
+
+$PAR
+Note: your answer must be written using "pi" for \(\pi\).
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+ANS(List($ans)->cmp());
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch8/SSA-multiple.pg b/Contrib/METU-NCC/MAT100/Ch8/SSA-multiple.pg
new file mode 100644
index 0000000000..6e85073170
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch8/SSA-multiple.pg
@@ -0,0 +1,84 @@
+## BEGIN_DESCRIPTION
+##  Law of cosines SSA (multiple lengths)
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Triangle trigonometry)
+## DBsection(Law of sines or law of cosines (side-side-angle))
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("SSA law of cosines (multiple integer answers)");
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->strings->add(none=>{});
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+
+
+@s = ("a","b","c")[pick(3,0..2)];
+@S = map { uc $_ } @s ;
+
+($r,$s) = pick(2,(1..7));
+
+$v[1] = Real($r+$s);              $v[0] = $v[1]**2 - $r*$s;
+$v[2] = Formula("sqrt($v[0])");
+
+if ( ($s[1] cmp $s[2]) == 1 ) {
+ @s[1,2] = @s[2,1]; 
+ @v[1,2] = @v[2,1];
+}
+$ans[0] = List($r,$s);
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find suitable value(s) for the side \($s[0]\) (if there are any) so that 
+\(\triangle ABC\) is the triangle with \($S[2]=60^\circ\), \($s[1]=$v[1]\), 
+and \($s[2]=$v[2]\).
+$PAR
+
+\($s[0] = \) \{$ans[0]->ans_rule();\}
+
+$PAR
+(If no values are possible, enter 'none'.)
+
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Ch8/SSA-one.pg b/Contrib/METU-NCC/MAT100/Ch8/SSA-one.pg
new file mode 100644
index 0000000000..36deba519e
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Ch8/SSA-one.pg
@@ -0,0 +1,85 @@
+## BEGIN_DESCRIPTION
+##  Law of cosines SSA (one length)
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Trigonometry)
+## DBchapter(Triangle trigonometry)
+## DBsection(Law of sines or law of cosines (side-side-angle))
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Level(2)
+## Language(en)
+## MO(1)
+###############################################
+
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("SSA law of cosines (one integer answer)");
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->strings->add(none=>{});
+Context()->flags->set(
+   reduceConstants => 0,
+   reduceConstantFunctions => 0,
+);
+
+
+@s = ("a","b","c")[pick(3,0..2)];
+@S = map { uc $_ } @s ;
+
+($r,$s) = PGsort (sub { $_[0] < $_[1] }, pick(2,(1..7)));         
+$r *= -1;
+
+$v[1] = Real($r+$s);              $v[0] = $v[1]**2 - $r*$s;
+$v[2] = Formula("sqrt($v[0])");
+
+if ( ($s[1] cmp $s[2]) == 1 ) {
+ @s[1,2] = @s[2,1]; 
+ @v[1,2] = @v[2,1];
+}
+$ans[0] = List($s);
+
+Context()->texStrings;
+
+BEGIN_TEXT
+
+Find suitable value(s) for the side \($s[0]\) (if there are any) so that 
+\(\triangle ABC\) is the triangle with \($S[2]=60^\circ\), \($s[1]=$v[1]\), 
+and \($s[2]=$v[2]\).
+$PAR
+
+\($s[0] = \) \{$ans[0]->ans_rule();\}
+
+$PAR
+(If no values are possible, enter 'none'.)
+
+
+END_TEXT
+
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+foreach (0..$#ans) { ANS($ans[$_]->cmp()); }
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify1.pg b/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify1.pg
new file mode 100644
index 0000000000..d73530039e
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify1.pg
@@ -0,0 +1,98 @@
+## BEGIN_DESCRIPTION
+##  Quadratic substitution  
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Algebra of real numbers and simplifying expressions)
+## DBsection(Simplifying expressions)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(4)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGunion.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "contextLimitedPolynomial.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("Factor and cancel");
+
+Context("Numeric");
+Context()->variables->are(x=>"Real",y=>"Real");
+Context()->noreduce('(-x)-y','(-x)+y');
+
+$a = random(1,4);
+
+$s = random(-1,1,2);
+
+@expr = (Formula("x^3+$s*($a)^3"),
+         Formula("x^2-($a)^2"));
+
+
+@expr = map { $_->reduce } @expr; 
+
+
+Context("LimitedPolynomial");
+
+@ans = (Formula("x^2-$s*$a*x+($a)^2"),
+        Formula("x - $s*$a"));
+
+if (random(0,1)==1) {@expr=@expr[(1,0)]; @ans=@ans[(1,0)];}
+
+
+$frac = "\frac{(" . $expr[0]->TeX . ")}{(" . $expr[1]->TeX . ")} "; 
+
+
+if ($displayMode eq 'TeX') {
+  $displayfrac =
+  "\[ $frac = ".$ans[0]->ans_rule(10).$ans[1]->ans_rule(10)." \]";
+} else {
+  $displayfrac =
+  ColumnTable(
+  "\( \displaystyle $frac = \)",
+  $ans[0]->ans_rule(20).$BR.$HR.$ans[1]->ans_rule(20),
+  indent => 0, separation => 10, valign => "MIDDLE"
+  );
+}
+
+
+Context()->texStrings;
+
+BEGIN_TEXT
+Factor and simplify.  Assume any factors you cancel are not zero
+$PAR
+$BCENTER
+$displayfrac
+$ECENTER
+
+
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+
+map { ANS($_->cmp()) } @ans;
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify2.pg b/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify2.pg
new file mode 100644
index 0000000000..0737326c49
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/ChR/R.4_Simplify2.pg
@@ -0,0 +1,102 @@
+## BEGIN_DESCRIPTION
+##  Factoring formulas and simplification
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Algebra of real numbers and simplifying expressions)
+## DBsection(Simplifying expressions)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## MO(1)
+## Static(0)
+## Level(4)
+## Language(en)
+###############################################
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGunion.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+
+COMMENT("Factor and cancel");
+
+Context("Numeric");
+Context()->variables->are(x=>"Real");
+Context()->noreduce('(-x)-y','(-x)+y');
+Context()->operators->undefine('/',' /','/ ','//');
+
+
+($a,$b) = pick(2,(1..4));
+
+($s,$t) = map { random(-1,1,2) } (1,2);
+
+@expr = (Formula("x^3+$s*($a)^3"), Formula("x^2-($b)^2"),
+         Formula("x^2-($a)^2"),    Formula("x^3+$t*($b)^3"));
+
+@expr = map { $_->reduce } @expr; 
+
+@ans = (Formula("(x^2-$s*$a*x+($a)^2)(x^2-$t*$b*x+($b)^2)")->reduce,
+        Formula("(x - $s*$a)(x - $t*$b)")->reduce);
+
+if (random(0,1)==1) {
+  @expr=@expr[(0,3,2,1)];
+  @ans = (Formula("(x^2-$s*$a*x+($a)^2)(x - $t*$b)")->reduce,
+          Formula("(x - $s*$a)(x^2-$t*$b*x+($b)^2)")->reduce);
+}
+
+if (random(0,1)==1) {@expr=@expr[(3,2,1,0)];}
+
+
+$frac = "\frac{(" . $expr[0]->TeX . ")}{(" . $expr[1]->TeX . ")} \div " . 
+        "\frac{(" . $expr[2]->TeX . ")}{(" . $expr[3]->TeX . ")}"; 
+
+
+if ($displayMode eq 'TeX') {
+  $displayfrac =
+  "\[ $frac = ".$ans[0]->ans_rule(10).$ans[1]->ans_rule(10)." \]";
+} else {
+  $displayfrac =
+  ColumnTable(
+  "\( \displaystyle $frac = \)",
+  $ans[0]->ans_rule(20).$BR.$HR.$ans[1]->ans_rule(20),
+  indent => 0, separation => 10, valign => "MIDDLE"
+  );
+}
+
+
+Context()->texStrings;
+
+BEGIN_TEXT
+Factor and simplify.  Assume any factors you cancel are not zero
+$PAR
+$BCENTER
+$displayfrac
+$ECENTER
+
+
+END_TEXT
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+
+map { ANS($_->cmp()) } @ans;
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT100/Table_Abs1.pg b/Contrib/METU-NCC/MAT100/Table_Abs1.pg
new file mode 100644
index 0000000000..b3fb5ef42b
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Table_Abs1.pg
@@ -0,0 +1,134 @@
+## BEGIN_DESCRIPTION
+##  Complete sign table for sums of absolute value functions
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Absolute value expressions and functions)
+## DBsection(Absolute value inequalities)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Date(October 2021)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+
+DOCUMENT();
+
+loadMacros(
+"PGstandard.pl",
+"PGcourse.pl",
+"MathObjects.pl",
+"parserPopUp.pl",
+"niceTables.pl",
+"contextFraction.pl"
+);
+
+TEXT(beginproblem());
+
+COMMENT('|ax+b|+c (randomly flipped)');
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+}
+
+Context("Fraction");
+
+#######################
+# Sign table constants
+#
+
+$dne = "~~x{2205}";
+#$dne = "X";
+
+@popPN = (PopUp([" ","+","-"],"+"), 
+          PopUp([" ","+","-"],"-")); 
+@popZ = (PopUp([" ","0","$dne"],"0"), 
+         PopUp([" ","0","$dne"],"$dne")); 
+
+$br = "border-right: 3px solid;";
+$bb = "border-bottom: 3px solid; height: 2px;";
+$ht = "height:2px;";
+
+#
+########################
+
+$a = random(2,5);
+$b = non_zero_random(-6,6);
+$c = random(1,10);
+
+$f = Formula("abs($a x - $b) - $c")->reduce;
+
+if (random(0,1)==1) {
+  $f = Formula("$c - abs($a x - $b)")->reduce;
+}
+
+@x = (Fraction($b-$c,$a), Fraction($b+$c,$a));
+
+@pop_Zer = ($popZ[0], $popZ[0]);
+
+@pop_f = ( 
+  (($f->eval(x=>$x[0]-1) > 0)         ? $popPN[0] : $popPN[1]) , 
+  (($f->eval(x=>($x[0]+$x[1])/2) > 0) ? $popPN[0] : $popPN[1]) , 
+  (($f->eval(x=>$x[1]+1) > 0)         ? $popPN[0] : $popPN[1])
+);
+
+
+Context()->texStrings;
+BEGIN_TEXT
+
+Fill in the sign table for the expression 
+\(\ \ \displaystyle f(x) = $f \).
+
+$PAR
+\{DataTable(
+[
+  ["\(x\)","",
+    [ans_rule(2),colspan=>2],"",
+    [ans_rule(2),colspan=>2],"" ],
+  [ ["",cellcss=>$bb],["",cellcss=>$bb],["",cellcss=>$bb.$br],
+    ["",cellcss=>$bb],["",cellcss=>$bb],["",cellcss=>$bb.$br],
+    ["",cellcss=>$bb],["",cellcss=>$bb] ],
+  [ ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
+    ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
+    ["",cellcss=>$ht],["",cellcss=>$ht] ],
+  ["\(f\)",$pop_f[0]->menu(),["0",colspan=>2],
+           $pop_f[1]->menu(),["0",colspan=>2],
+	   $pop_f[2]->menu() ]
+], 'align =>ccc|ccc|cc', midrules=>1
+);\}
+
+$PAR
+In the row for \(x\):
+$BR\(\quad \bullet\ \) 
+fill in \(x\)-values on number line where \(f\) is zero.
+$BR
+In the row for \(f\):
+$BR\(\quad \bullet\ \) 
+choose "\(+\)" or "\(-\)" on  ${BBOLD}intervals${EBOLD} 
+  to indicate \(f\) is ${BBOLD}positive${EBOLD} or ${BBOLD}negative${EBOLD}.
+
+
+
+
+END_TEXT
+Context()->normalStrings;
+
+ANS( $x[0]->cmp() );
+ANS( $x[1]->cmp() );
+
+ANS( $pop_f[0]->cmp() ); 
+ANS( $pop_f[1]->cmp() );
+ANS( $pop_f[2]->cmp() ); 
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+       
diff --git a/Contrib/METU-NCC/MAT100/Table_Abs.pg b/Contrib/METU-NCC/MAT100/Table_Abs2.pg
similarity index 84%
rename from Contrib/METU-NCC/MAT100/Table_Abs.pg
rename to Contrib/METU-NCC/MAT100/Table_Abs2.pg
index 26b0acf955..2c006bc7f3 100644
--- a/Contrib/METU-NCC/MAT100/Table_Abs.pg
+++ b/Contrib/METU-NCC/MAT100/Table_Abs2.pg
@@ -104,7 +104,7 @@ if (random(0,1)==1) {
 Context()->texStrings;
 BEGIN_TEXT
 
-Fill in the sign table for the function 
+Fill in the sign table for the expression
 \(\ \ \displaystyle f(x) = $f \).
 
 $PAR
@@ -119,8 +119,8 @@ $PAR
   [ ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
     ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
     ["",cellcss=>$ht],["",cellcss=>$ht] ],
-  ["\(f\)",$pop_f[0]->menu(),[$pop_Zer[0]->menu(),colspan=>2],
-           $pop_f[1]->menu(),[$pop_Zer[1]->menu(),colspan=>2],
+  ["\(f\)",$pop_f[0]->menu(),["0",colspan=>2],
+           $pop_f[1]->menu(),["0",colspan=>2],
 	   $pop_f[2]->menu() ]
 ], 'align =>ccc|ccc|cc', midrules=>1
 );\}
@@ -128,15 +128,12 @@ $PAR
 $PAR
 In the row for \(x\):
 $BR\(\quad \bullet\ \) 
-fill in \(x\)-values on number line where \(f\) is zero or does not exist.
+fill in \(x\)-values on number line where \(f\) is zero.
 $BR
 In the row for \(f\):
 $BR\(\quad \bullet\ \) 
-mark ${BBOLD}intervals${EBOLD} as "\(+\)" or "\(-\)" 
-  to indicate \(f\) is ${BBOLD}positive${EBOLD} or ${BBOLD}negative${EBOLD}; and
-$BR\(\quad \bullet\ \) 
-mark ${BBOLD}points${EBOLD} as "\(0\)" or "${BTT}$dne${ETT}" 
-  to indicate \(f\) is ${BBOLD}zero${EBOLD} or does ${BBOLD}not exist${EBOLD}.
+choose "\(+\)" or "\(-\)" on  ${BBOLD}intervals${EBOLD}
+  to indicate \(f\) is ${BBOLD}positive${EBOLD} or ${BBOLD}negative${EBOLD}.
 
 
 
@@ -147,8 +144,8 @@ Context()->normalStrings;
 ANS( $x[0]->cmp() );
 ANS( $x[1]->cmp() );
 
-ANS( $pop_f[0]->cmp() ); ANS( $pop_Zer[0]->cmp() ); 
-ANS( $pop_f[1]->cmp() ); ANS( $pop_Zer[1]->cmp() ); 
+ANS( $pop_f[0]->cmp() ); 
+ANS( $pop_f[1]->cmp() );
 ANS( $pop_f[2]->cmp() ); 
 
 
diff --git a/Contrib/METU-NCC/MAT100/Table_Abs3.pg b/Contrib/METU-NCC/MAT100/Table_Abs3.pg
new file mode 100644
index 0000000000..c4b2af2b33
--- /dev/null
+++ b/Contrib/METU-NCC/MAT100/Table_Abs3.pg
@@ -0,0 +1,162 @@
+## BEGIN_DESCRIPTION
+##  Complete sign table for sums of absolute value functions
+## END_DESCRIPTION
+##
+##############################################
+## DBsubject(Algebra)
+## DBchapter(Absolute value expressions and functions)
+## DBsection(Absolute value inequalities)
+## Institution(METU-NCC)
+## Author(Benjamin Walter)
+## Date(October 2021)
+## MO(1)
+## Static(0)
+## Level(2)
+## Language(en)
+###############################################
+
+
+
+DOCUMENT();
+
+loadMacros(
+"PGstandard.pl",
+"PGcourse.pl",
+"MathObjects.pl",
+"parserPopUp.pl",
+"niceTables.pl",
+"contextFraction.pl"
+);
+
+TEXT(beginproblem());
+
+COMMENT('random slopes could make answers ugly...');
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out;
+}
+
+Context("Fraction");
+
+#######################
+# Sign table constants
+#
+
+$dne = "~~x{2205}";
+#$dne = "X";
+
+@popPN = (PopUp([" ","+","-"],"+"), 
+          PopUp([" ","+","-"],"-")); 
+@popZ = (PopUp([" ","0","$dne"],"0"), 
+         PopUp([" ","0","$dne"],"$dne")); 
+
+$br = "border-right: 3px solid;";
+$bb = "border-bottom: 3px solid; height: 2px;";
+$ht = "height:2px;";
+
+#
+########################
+
+@a = PGsort(sub {$_[0] < $_[1]}, pick(3,(-4..-1,1..4)));
+@m = map { random(1,3) } @a; 
+
+$f = Formula("$m[0] abs(x-$a[0]) + $m[1] abs(x-$a[1]) + $m[2] abs(x-$a[2])")->reduce;
+
+@crit  = ($f->eval(x=>$a[0]),$f->eval(x=>$a[1]),$f->eval(x=>$a[2]));
+@crits = PGsort(sub {$_[0] < $_[1]}, @crit);
+
+do { $b = random($crits[0]+1,$crits[2]+3); } 
+until (($b != $crits[1]) && ($b != $crits[2]));
+
+$f = Formula("$f-$b")->reduce;
+
+@x = ();
+
+if ($b > $crit[0]) {
+  push(@x, (
+   Fraction($m[0]*$a[0]+$m[1]*$a[1]+$m[2]*$a[2]-$b,
+            $m[0]+$m[1]+$m[2])->reduce
+  ));
+}
+if ($b == (PGsort(sub {$_[0] < $_[1]}, ($b,$crit[0],$crit[1])))[1]) {
+  push(@x, (
+   Fraction(-$m[0]*$a[0]+$m[1]*$a[1]+$m[2]*$a[2]-$b,
+            -$m[0]+$m[1]+$m[2])->reduce
+  ));
+}
+if ($b == (PGsort(sub {$_[0] < $_[1]}, ($b,$crit[1],$crit[2])))[1]) {
+  push(@x, (
+   Fraction(-$m[0]*$a[0]-$m[1]*$a[1]+$m[2]*$a[2]-$b,
+            -$m[0]-$m[1]+$m[2])->reduce
+  ));
+}
+if ($b > $crit[2]) { 
+  push(@x, (
+   Fraction($m[0]*$a[0]+$m[1]*$a[1]+$m[2]*$a[2]+$b,
+            $m[0]+$m[1]+$m[2])->reduce
+  ));
+}
+
+@pop_Zer = ($popZ[0], $popZ[0]);
+
+@pop_f = ( 
+  (($f->eval(x=>$x[0]-1) > 0)         ? $popPN[0] : $popPN[1]) , 
+  (($f->eval(x=>($x[0]+$x[1])/2) > 0) ? $popPN[0] : $popPN[1]) , 
+  (($f->eval(x=>$x[1]+1) > 0)         ? $popPN[0] : $popPN[1])
+);
+
+
+Context()->texStrings;
+BEGIN_TEXT
+
+Fill in the sign table for the expression 
+\(\ \ \displaystyle f(x) = $f \).
+
+$PAR
+\{DataTable(
+[
+  ["\(x\)","",
+    [ans_rule(2),colspan=>2],"",
+    [ans_rule(2),colspan=>2],"" ],
+  [ ["",cellcss=>$bb],["",cellcss=>$bb],["",cellcss=>$bb.$br],
+    ["",cellcss=>$bb],["",cellcss=>$bb],["",cellcss=>$bb.$br],
+    ["",cellcss=>$bb],["",cellcss=>$bb] ],
+  [ ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
+    ["",cellcss=>$ht],["",cellcss=>$ht],["",cellcss=>$ht.$br],
+    ["",cellcss=>$ht],["",cellcss=>$ht] ],
+  ["\(f\)",$pop_f[0]->menu(),["0",colspan=>2],
+           $pop_f[1]->menu(),["0",colspan=>2],
+	   $pop_f[2]->menu() ]
+], 'align =>ccc|ccc|cc', midrules=>1
+);\}
+
+$PAR
+In the row for \(x\):
+$BR\(\quad \bullet\ \) 
+fill in \(x\)-values on number line where \(f\) is zero.
+$BR
+In the row for \(f\):
+$BR\(\quad \bullet\ \) 
+choose "\(+\)" or "\(-\)" on  ${BBOLD}intervals${EBOLD} 
+  to indicate \(f\) is ${BBOLD}positive${EBOLD} or ${BBOLD}negative${EBOLD}.
+
+
+
+
+END_TEXT
+Context()->normalStrings;
+
+ANS( $x[0]->cmp() );
+ANS( $x[1]->cmp() );
+
+ANS( $pop_f[0]->cmp() ); 
+ANS( $pop_f[1]->cmp() );
+ANS( $pop_f[2]->cmp() ); 
+
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+       
diff --git a/Contrib/METU-NCC/MAT100/Table_Rat.pg b/Contrib/METU-NCC/MAT100/Table_Rat.pg
index dacd3990d6..d27df96a35 100644
--- a/Contrib/METU-NCC/MAT100/Table_Rat.pg
+++ b/Contrib/METU-NCC/MAT100/Table_Rat.pg
@@ -43,9 +43,11 @@ $dne = "~~x{2205}";
 @c = ([random(1,3),          random(-3,-1)],
       [non_zero_random(-3,3),non_zero_random(-3,3)]);
 do {$c[0][1] =         random(-3,-1);} while (abs($c[0][0])==abs($c[0][1]));
-do {$c[0][2] = non_zero_random(-3,3);} while (abs($c[0][0])==abs($c[0][2]));
+do {$c[0][2] = non_zero_random(-3,3);} while (($c[0][0]==$c[0][2]) ||
+                                              ($c[0][1]==$c[0][2]));
 do {$c[1][1] = non_zero_random(-3,3);} while (abs($c[1][0])==abs($c[1][1]));
-do {$c[1][2] = non_zero_random(-3,3);} while (abs($c[1][0])==abs($c[1][2]));
+do {$c[1][2] = non_zero_random(-3,3);} while (($c[1][0]==$c[1][2]) || 
+                                              ($c[1][1]==$c[1][2]));
 
 my @S;
 $S[0] = non_zero_random(-1,1);
diff --git a/Contrib/METU-NCC/MAT101/Chapter0/Exp_Solve.pg b/Contrib/METU-NCC/MAT101/Chapter0/Exp_Solve.pg
index 429775bbd7..91ddb4127b 100644
--- a/Contrib/METU-NCC/MAT101/Chapter0/Exp_Solve.pg
+++ b/Contrib/METU-NCC/MAT101/Chapter0/Exp_Solve.pg
@@ -30,6 +30,8 @@ Context()->variables->are(x=>"Real",y=>"Real");
 
 my $a; my $b; my $c; my $d; my $ab;
 
+######## (A)
+
 ($a,$b,$c) = (random(2,4),random(2,5),non_zero_random(-4,4));
 $d =  $b*$a+$c;
 
@@ -37,7 +39,7 @@ $expr[0] = Formula("$b sqrt(x)+$c")->reduce;
 $expr[0] = $expr[0]->TeX . " = $d" ;  
 $ans[0] =  Real($a**2);
 
-#########
+######### (B)
 
 ($a,$b,$c) = (random(2,4),random(2,5),non_zero_random(-4,4));
 $d =  $b*$a;
@@ -47,7 +49,7 @@ $expr[1] = $expr[1]->TeX . " = $d" ;
 $ans[1] =  Real($a**2-$c);
 
 
-#########
+######### (C)
 
 
 ($a,$b,$c) = (random(2,4),random(2,4),random(2,3));
@@ -57,7 +59,7 @@ $expr[2] = "$b x^{1/$c}= $d";
 $ans[2]  =  Real($a**$c);
 
 
-#########
+######### (D)
 
 ($a,$b,$c) = (random(2,3),random(3,5),random(2,4));
 $d =  $c*$a**$b;
@@ -65,6 +67,8 @@ $d =  $c*$a**$b;
 $expr[3] = "$c x^{-$b}= $d";
 $ans[3]  =  Fraction(1,$a);
 
+if ($b%2==0) { $ans[3] = List($ans[3],-$ans[3]) };
+
 
 #########
 
diff --git a/Contrib/METU-NCC/MAT101/Chapter3/Lines-v2.pg b/Contrib/METU-NCC/MAT101/Chapter3/Lines-v2.pg
new file mode 100644
index 0000000000..e5eeee703e
--- /dev/null
+++ b/Contrib/METU-NCC/MAT101/Chapter3/Lines-v2.pg
@@ -0,0 +1,107 @@
+## DBsubject(Algebra)
+## DBchapter(Linear equations and functions)
+## DBsection(Equations of lines: general)
+## Level(2)
+## Author(Benjamin Walter)
+## Institution(METU-NCC)
+## Language(en)
+## MO(1)
+## Static(0)
+
+DOCUMENT();        # This should be the first executable line in the problem.
+
+loadMacros(
+  "PGstandard.pl",
+  "PGchoicemacros.pl",
+  "PGcourse.pl",
+  "MathObjects.pl",
+  "parserImplicitPlane.pl",
+  "contextFraction.pl"
+);
+
+sub pick {
+  my ($k, @in) = @_;
+  my @out = ();
+  while (@out < $k) { push( @out, splice(@in, random(0,$#in), 1) ); }
+  @out; 
+};
+
+TEXT(beginproblem());
+Context("Fraction");
+Context()->variables->are(x=>"Real");
+
+my @c; my @m; 
+
+@c = pick(4,(-5..-1,1..5));  
+do {
+ @m = (Fraction(pick(2,(2..5)))->reduce,
+       Fraction(pick(2,(2..5)))->reduce); 
+} while ($m[0]==$m[1]);
+$m[random(0,1)] *= -1; 
+Context()->texStrings;
+$expr[0] = "Through \(($c[0],\,$c[1])\) with slope \($m[0]\)";
+Context()->normalStrings;
+$ans[0]  = Formula("$m[0] (x-$c[0]) + $c[1]")->reduce;
+
+$expr[1] = "With \(y($c[2])=$c[3]\) and slope \($m[1]\)";
+$ans[1]  = Formula("$m[1] (x-$c[2]) + $c[3]")->reduce;
+
+do { @c = (pick(2,(-5..-1,1..5)),pick(2,(-5..-1,1..5))); }
+until (($c[0]!=$c[2]) && ($c[1] != $c[3]));
+$expr[2] = "Through \(($c[0],\,$c[1])\) and \(($c[2],\,$c[3])\)";
+$ans[2]  = Formula("($c[3]-$c[1])/($c[2]-$c[0]) (x-$c[0]) + $c[1]")->reduce;
+
+do { @c = (pick(2,(-5..-1,1..5)),pick(2,(-5..-1,1..5))); }
+until (($c[0]!=$c[2]) && ($c[1] != $c[3]));
+$expr[3] = "With \(y($c[0])=$c[1]\) and \(y($c[2])=$c[3]\)";
+$ans[3]  = Formula("($c[3]-$c[1])/($c[2]-$c[0]) (x-$c[0]) + $c[1]")->reduce;
+
+$c[0] = non_zero_random(-5,5);
+$m[0] = Fraction(non_zero_random(-5,5),random(2,5))->reduce;
+Context()->texStrings;
+$expr[4] = "With \(y\)-intercept \($c[0]\) and slope \($m[0]\)";
+Context()->normalStrings;
+$ans[4]  = Formula("$m[0] x + $c[0]")->reduce;
+
+@c = pick(2,(-5..-1,1..5));
+$expr[5] = "With \(y\)-intercept \($c[0]\) and \(x\)-intercept \($c[1]\)";
+$ans[5]  = Formula("-$c[0]/$c[1] x + $c[0]");
+
+
+Context("ImplicitPlane");
+Context()->variables->are(x=>"Real",y=>"Real");
+
+@ans = map { ImplicitPlane("y=$_") } @ans;
+
+my @i = pick(4,(0,2,4,5));
+@expr = @expr[@i]; @ans = @ans[@i];
+
+@index = ("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O");
+
+Context()->texStrings;
+BEGIN_TEXT
+
+Write formulas for the following lines.
+END_TEXT
+for ($i=0;$i<=$#expr;$i++) {
+BEGIN_TEXT
+
+$PAR
+$BBOLD ($index[$i]) $EBOLD  $SPACE $SPACE 
+ $expr[$i] $BR
+ \(\quad \) \{ans_rule(15);\}
+
+END_TEXT
+}
+
+Context()->normalStrings;
+
+$showPartialCorrectAnswers = 1;
+
+for ($i=0;$i<=$#ans;$i++) {
+  ANS( $ans[$i]->cmp() );
+}
+
+
+ENDDOCUMENT();        # This should be the last executable line in the problem.
+
diff --git a/Contrib/METU-NCC/MAT101/Chapter8/Probability-3.pg b/Contrib/METU-NCC/MAT101/Chapter8/Probability-3.pg
index 9b1d0c3060..0d351076af 100644
--- a/Contrib/METU-NCC/MAT101/Chapter8/Probability-3.pg
+++ b/Contrib/METU-NCC/MAT101/Chapter8/Probability-3.pg
@@ -29,12 +29,11 @@ Context("IntegerFunctions");
 Context()->variables->are(x=>"Real");
 Context()->flags->set(reduceConstants=>0);
 
-$b = random(5,8);
-do { $g = random(5,8); } until ($g != $b);
+($b,$g) = pick(2,(5..8));
 $n = $b+$g;
 
 $k = random(4,min($g,$b));
-my $m = random(2,min($g,$b)-1);
+my $m = random(2,min($g,$b,$k)-1);
 
 my $i = random(0,1);
 
diff --git a/Contrib/METU-NCC/MAT101/Derivatives/Chain2.pg b/Contrib/METU-NCC/MAT101/Derivatives/Chain2.pg
index 75fbdca11a..79376c0f82 100644
--- a/Contrib/METU-NCC/MAT101/Derivatives/Chain2.pg
+++ b/Contrib/METU-NCC/MAT101/Derivatives/Chain2.pg
@@ -76,23 +76,23 @@ Compute derivatives of the following functions (be careful about parenthesis!):
 $PAR
 $BBOLD A.$EBOLD \(\quad \displaystyle f(x) = $f_text[0]\)
 $BR
-\(\quad f'(x) = \) \{ ans_box(2,40); \}
+\(\quad f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 $BBOLD B.$EBOLD \(\quad \displaystyle f(x) = $f_text[1]\)
 $BR
-\(\quad f'(x) = \) \{ ans_box(3,40); \}
+\(\quad f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 $BBOLD C.$EBOLD \(\quad \displaystyle f(x) = $f_text[2]\)
 $BR
-\(\quad f'(x) = \) \{ ans_box(2,40); \}
+\(\quad f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 
 $BBOLD D.$EBOLD \(\quad \displaystyle f(x) = $f_text[3]\)
 $BR
-\(\quad f'(x) = \) \{ ans_box(3,40); \}
+\(\quad f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 
diff --git a/Contrib/METU-NCC/MAT101/Derivatives/Product.pg b/Contrib/METU-NCC/MAT101/Derivatives/Product.pg
index 43cf921011..630b51b3df 100644
--- a/Contrib/METU-NCC/MAT101/Derivatives/Product.pg
+++ b/Contrib/METU-NCC/MAT101/Derivatives/Product.pg
@@ -82,12 +82,12 @@ Compute derivatives of the following functions:
 $PAR
 $BBOLD A.$EBOLD \(\quad \displaystyle f(x) = $text_prod\)
 $BR
-\(\quad \ \ f'(x) = \) \{ ans_box(3,40); \}
+\(\quad \ \ f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 $BBOLD B.$EBOLD \(\quad \displaystyle f(x) = $text_quot\)
 $BR
-\(\quad f'(x) = \) \{ ans_box(3,40); \}
+\(\quad f'(x) = \) \{ ans_rule(40); \}
 $PAR
 
 
diff --git a/Contrib/METU-NCC/MAT101/Final/Basics2.pg b/Contrib/METU-NCC/MAT101/Final/Basics2.pg
index b43a56c320..5ce6d2a49a 100644
--- a/Contrib/METU-NCC/MAT101/Final/Basics2.pg
+++ b/Contrib/METU-NCC/MAT101/Final/Basics2.pg
@@ -75,7 +75,7 @@ $counter = 0;
 do {
 BEGIN_TEXT
 $BBOLD $items[$counter] $EBOLD
- \(\displaystyle \frac{d}{dx} \left[ $F[$counter] \right] = \) \{ ans_box(3,20); \}
+ \(\displaystyle \frac{d}{dx} \left[ $F[$counter] \right] = \) \{ ans_rule(20); \}
 $PAR
 END_TEXT
 $counter++;
diff --git a/Contrib/METU-NCC/MAT101/Final/Tangent.pg b/Contrib/METU-NCC/MAT101/Final/Tangent.pg
index 3b7357225b..ef450c2c64 100644
--- a/Contrib/METU-NCC/MAT101/Final/Tangent.pg
+++ b/Contrib/METU-NCC/MAT101/Final/Tangent.pg
@@ -56,12 +56,12 @@ do {
  }
 } until ($unique == 1);
 
-$a = random(0,2);
+$a = random(0,1);
 
 $Tangent1 = Formula("$df[$a]*(x-($a+1)) + $f[$a]")->reduce;
 $Tangent2 = Formula("($df[$a]+1)*(x-($a+1)) + ($f[$a]+$a+1)")->reduce;
 $Tangent3 = Formula("($df[$a]*($a+1)+$f[$a])*(x-($a+1)) + $f[$a]*($a+1)")->reduce;
-$Tangent4 = Formula("$df[$a+1](x-($a+1)) + $f[$a+1]")->reduce;
+$Tangent4 = Formula("2*$df[2*$a+1](x-($a+1)) + $f[2*$a+1]")->reduce;
 
 $a++;
 
@@ -100,7 +100,7 @@ $BBOLD (C) $EBOLD The tangent line to \(y= x  $f\) at \(x=$a\).
 
 $PAR
 
-$BBOLD (D) $EBOLD The tangent line to \(y= f{\small(x+1)}\) at \(x=$a\).
+$BBOLD (D) $EBOLD The tangent line to \(y= f{\small(2x)}\) at \(x=$a\).
   $BR \(\quad y = \)\{ans_rule(10);\}  
 
 
diff --git a/Contrib/METU-NCC/MAT101/Integrals/Surplus.pg b/Contrib/METU-NCC/MAT101/Integrals/Surplus.pg
index 170410da81..5e1e2f7057 100644
--- a/Contrib/METU-NCC/MAT101/Integrals/Surplus.pg
+++ b/Contrib/METU-NCC/MAT101/Integrals/Surplus.pg
@@ -108,6 +108,11 @@ $PAR
 $PAR$BR$PAR
 
 
+END_TEXT
+
+
+BEGIN_TEXT
+
 $BBOLD B. $EBOLD Find the $problem[$p[0]].
 $PAR
 $int[$p[0]]
@@ -122,12 +127,12 @@ END_TEXT
 Context()->normalStrings;
 
 ANS(Real("$eq_quantity")->cmp()); ANS(Real("0")->cmp());
-ANS($diff[$p[0]]->cmp());
-ANS($surp[$p[0]]->cmp());
+ANS($diff[0]->cmp());
+ANS($surp[0]->cmp());
 
 ANS(Real("$eq_quantity")->cmp()); ANS(Real("0")->cmp());
-ANS($diff[$p[1]]->cmp());
-ANS($surp[$p[1]]->cmp());
+ANS($diff[1]->cmp());
+ANS($surp[1]->cmp());
 
 ANS( Real("$eq_quantity")->cmp() );
 ANS( Real("$eq_price")->cmp() );
diff --git a/Contrib/METU-NCC/MAT101/Midterm/log.pg b/Contrib/METU-NCC/MAT101/Midterm/log.pg
index 4af13d2bf1..649b7f8cfb 100644
--- a/Contrib/METU-NCC/MAT101/Midterm/log.pg
+++ b/Contrib/METU-NCC/MAT101/Midterm/log.pg
@@ -67,7 +67,7 @@ $expr2[1] = Formula("$c[3]");
 $ans2 = Fraction($c[2]-$c[1],$c[0]);
 
 
-do { @c = (random(-4,-1),random(1,4)); }
+do { @c = (random(-6,-1),random(2,5)); }
 until ($c[0]+$c[1] != 0);
 
 $expr3[0] = "\log_{x} (" . 
diff --git a/Contrib/METU-NCC/R/data_create.pg b/Contrib/METU-NCC/R/data_create.pg
index f24ee01771..c946ca02ec 100644
--- a/Contrib/METU-NCC/R/data_create.pg
+++ b/Contrib/METU-NCC/R/data_create.pg
@@ -192,11 +192,12 @@ $BR
 
 $PAR
 
-\{ knowlLink("Weird side note",  
-     value=>' $SPACE You can also store data using an arrow in the other direction. For example: $BR
-     <code style="Font-family:courier;font-size:inherit;"> 
-     $SPACE $SPACE 17 $SPACE-> Age $BR
-     $SPACE "Ali" -> Name </code>');
+\{ knowlLink("Weird side note", value=> <<EOF);  
+$SPACE You can also store data using an arrow in the other direction. For example: $BR
+<code style="Font-family:courier;font-size:inherit;"> 
+$SPACE $SPACE 17 $SPACE-> Age $BR
+$SPACE "Ali" -> Name </code>
+EOF
 \}
 
 END_TEXT
diff --git a/Contrib/METU-NCC/R/data_frame2.pg b/Contrib/METU-NCC/R/data_frame2.pg
index 76ed4cefe4..d6ddd07944 100644
--- a/Contrib/METU-NCC/R/data_frame2.pg
+++ b/Contrib/METU-NCC/R/data_frame2.pg
@@ -208,22 +208,24 @@ DataTable([
 ],@Rbox_out,align=>'clrrp{30px}|p{10px}lrrp{30px}'); 
 \}
 $PAR
-\{ knowlLink("Code for Family", value=>' 
- Family <- data.frame($BR        
-$SPACE $SPACE Name = c("Benjamin","Annabet","Charlie","Daddy","Mama"),$BR
-$SPACE $SPACE Age  = c(15, 11, 7, 41, 41),$BR
+\{ knowlLink("Code for Family", url=>'', type=>'', value=> <<EOF); 
+Family <- data.frame($BR        
+$SPACE $SPACE Name $SPACE = c("Benjamin","Annabet","Charlie","Daddy","Mama"),$BR
+$SPACE $SPACE Age $SPACE$SPACE $SPACE = c(15, 11, 7, 41, 41),$BR
 $SPACE $SPACE Gender = factor( c("M", "F", "M", "M", "F") ),$BR
 $SPACE $SPACE stringsAsFactors = FALSE$BR
-)'
-); \}
+)
+EOF
+ \}
 $PAR
-\{ knowlLink("Code for Family_named", value=>'
- Family_named <- data.frame($BR        
+\{ knowlLink("Code for Family_named", value=> <<EOF);
+Family_named <- data.frame($BR        
 $SPACE $SPACE row.names = c("Benjamin","Annabet","Charlie","Daddy","Mama"),$BR
-$SPACE $SPACE Age  = c(15, 11, 7, 41, 41),$BR
-$SPACE $SPACE Gender = c("M", "F", "M", "M", "F")$BR
-)'
-); \}
+$SPACE $SPACE Age $SPACE $SPACE $SPACE $SPACE $SPACE$SPACE = c(15, 11, 7, 41, 41),$BR
+$SPACE $SPACE Gender $SPACE $SPACE$SPACE = c("M", "F", "M", "M", "F")$BR
+)
+EOF
+\}
 $PAR
 Columns of a data frame are accessed using $BCODE $DOLLAR$ECODE. 
 $BR For example, 
diff --git a/Contrib/METU-NCC/Statistics/P3_Cont/R_integrate2.pg b/Contrib/METU-NCC/Statistics/P3_Cont/R_integrate2.pg
index a55afe4cee..936a3dcf92 100644
--- a/Contrib/METU-NCC/Statistics/P3_Cont/R_integrate2.pg
+++ b/Contrib/METU-NCC/Statistics/P3_Cont/R_integrate2.pg
@@ -70,7 +70,7 @@ Context("ArbitraryString");
    String("integrate(function(x) {(x^2)    *$cf},$a,$b)"),
 );
 
-$R = rserve_eval($A[0]);
+#$R = rserve_eval($A[0]);
 
 
 
diff --git a/Contrib/METU-NCC/Statistics/S3_CI/CI_p.pg b/Contrib/METU-NCC/Statistics/S3_CI/CI_p.pg
index 1183583970..e8d2e62654 100644
--- a/Contrib/METU-NCC/Statistics/S3_CI/CI_p.pg
+++ b/Contrib/METU-NCC/Statistics/S3_CI/CI_p.pg
@@ -18,12 +18,13 @@
 DOCUMENT();
 
 loadMacros(
-   "PGstandard.pl",     # Standard macros for PG language
-   "MathObjects.pl",
-   "contextArbitraryString.pl",
-   "RserveClient.pl",
-   "PGcourse.pl",
-   "contextFraction.pl"
+	"PGstandard.pl",     # Standard macros for PG language
+	"MathObjects.pl",
+	"contextArbitraryString.pl",
+	"RserveClient.pl",
+	"PGcourse.pl",
+	"contextFraction.pl",
+	"scaffold.pl"
 );
 
 # Print problem number and point value (weight) for the problem
@@ -143,18 +144,45 @@ $BR
    \{ans_rule(35)\} 
 \(\Bigr) \)
 
+$PAR
+
+\{ knowlLink("(Reminder about R commands.)", value=> <<EOF);
+Recall that if \(Z\sim \mathrm{Normal}(0,1)\) 
+then the critical values of \(Z\) are computed in R by the command:
+$BR
+\(\qquad z_\alpha \  =\!= \   \) 
+    ${BTT}qnorm(\(1-\alpha\))${ETT}
+$BR
+For example 
+$BR $SPACE $SPACE $SPACE ${BTT}qnorm\((1-.05)\)${ETT} $SPACE $SPACE $SPACE 
+computes the critical value \(z_{5\%}\) where 
+\(\mathrm{P}\bigl(Z > z_{5\%}\bigr) =\!= 5\%\).
+EOF
+\}
+
 $PAR
 $HR
 $PAR
-You may use the embedded R window below to check your code and perform computations.$BR
+Click below to open an embedded R-window which you can use to check your 
+code or perform computations
+
+END_TEXT
+Scaffold::Begin(can_open=>"always",is_open=>"never");
+########################################################
+Section::Begin("$BBOLD Embedded R Window $EBOLD");
+
+BEGIN_TEXT
+
 ${BCENTER}
 $Rframe
 ${ECENTER}
 
-
-
 END_TEXT
 
+Section::End();
+########################################################
+Scaffold::End();
+
 Context()->normalStrings;
 
 #  Answers
diff --git a/Contrib/METU-NCC/Statistics/S3_CI/CI_t.pg b/Contrib/METU-NCC/Statistics/S3_CI/CI_t.pg
index c871e506e0..c9c0eb8362 100644
--- a/Contrib/METU-NCC/Statistics/S3_CI/CI_t.pg
+++ b/Contrib/METU-NCC/Statistics/S3_CI/CI_t.pg
@@ -18,11 +18,12 @@
 DOCUMENT();
 
 loadMacros(
-   "PGstandard.pl",     # Standard macros for PG language
-   "MathObjects.pl",
-   "contextArbitraryString.pl",
-   "RserveClient.pl",
-   "PGcourse.pl",
+	"PGstandard.pl",     # Standard macros for PG language
+	"MathObjects.pl",
+	"contextArbitraryString.pl",
+	"RserveClient.pl",
+	"PGcourse.pl",
+	"scaffold.pl"
 );
 
 # Print problem number and point value (weight) for the problem
@@ -101,28 +102,43 @@ $BR
 
 $PAR
 
-$PAR
-$HR
-$PAR
-You may use the embedded R window below to check your code and perform computations.$BR
-${BCENTER}
-$Rframe
-${ECENTER}
-$PAR
+\{ knowlLink("(Reminder about R commands.)", value=> <<EOF);
 Recall that if \(T\sim \mathrm{t}(n)\) 
 (i.e. \(t\)-distribution with \(n\) degrees of freedom)
 then the critical values of \(T\) are computed in R by the command:
 $BR
-\(\qquad t_\alpha \  =\!= \   \) 
-    ${BTT}\(-\)qt(\(\alpha,n\))${ETT}
+\(\qquad t_{\alpha,n} \  =\!= \   \) 
+    ${BTT}qt(\(1-\alpha,n\))${ETT}
 $BR
 For example 
-$BR $SPACE $SPACE $SPACE ${BTT}\(-\)qt\((.05,\;9)\)${ETT} $SPACE $SPACE $SPACE 
-computes the critical value \(t_{5\%}\) where 
-\(\mathrm{P}\bigl(T > t_{5\%}\bigr) =\!= 5\%\), and \(T\) has 9 degrees of freedom.
+$BR $SPACE $SPACE $SPACE ${BTT}qt\((1-.05,\;9)\)${ETT} $BR
+computes the critical value \(t_{5\%,9}\) where 
+\(\mathrm{P}\bigl(T \ge t_{5\%,9}\bigr) =\!= 5\%\), and \(T\) has 9 degrees of freedom.
+EOF
+\}
 
+$PAR
+$HR
+$PAR
+Click below to open an embedded R-window which you can use to check your 
+code or perform computations
 
 END_TEXT
+Scaffold::Begin(can_open=>"always",is_open=>"never");
+########################################################
+Section::Begin("$BBOLD Embedded R Window $EBOLD");
+
+BEGIN_TEXT
+
+${BCENTER}
+$Rframe
+${ECENTER}
+
+END_TEXT
+
+Section::End();
+########################################################
+Scaffold::End();
 
 Context()->normalStrings;
 
diff --git a/Contrib/METU-NCC/Statistics/S3_CI/CI_x.pg b/Contrib/METU-NCC/Statistics/S3_CI/CI_x.pg
index 5c846998a8..4697a9f910 100644
--- a/Contrib/METU-NCC/Statistics/S3_CI/CI_x.pg
+++ b/Contrib/METU-NCC/Statistics/S3_CI/CI_x.pg
@@ -18,11 +18,12 @@
 DOCUMENT();
 
 loadMacros(
-   "PGstandard.pl",     # Standard macros for PG language
-   "MathObjects.pl",
-   "contextArbitraryString.pl",
-   "RserveClient.pl",
-   "PGcourse.pl",
+	"PGstandard.pl",     # Standard macros for PG language
+	"MathObjects.pl",
+	"contextArbitraryString.pl",
+	"RserveClient.pl",
+	"PGcourse.pl",
+	"scaffold.pl"
 );
 
 # Print problem number and point value (weight) for the problem
@@ -81,29 +82,44 @@ $BR
 
 $PAR
 
-$PAR
-$HR
-$PAR
-You may use the embedded R window below to check your code and perform computations.$BR
-${BCENTER}
-$Rframe
-${ECENTER}
-$PAR
-Recall that if \(X\sim \chi^2(n)\) 
+\{ knowlLink("(Reminder about R commands.)", value=> <<EOF);
+Recall that if \(X\sim {\large \chi}^2(n)\) 
 ("Chi-squared with \(n\) degrees of freedom")
 then the critical values of \(X\) are computed in R by the command:
 $BR 
-\(\qquad \chi_\alpha \  =\!= \   \) 
-    ${BTT}qchisq\(\bigl(\alpha,n\bigr)\)${ETT}
+\(\qquad {\large \chi}_\alpha \  =\!= \   \) 
+    ${BTT}qchisq\(\bigl(1-\alpha,n\bigr)\)${ETT}
 $BR
 For example 
-$BR $SPACE $SPACE $SPACE ${BTT}qchisq\((.05,\;9)\)${ETT} $SPACE $SPACE $SPACE 
-computes the critical value \(\chi_{5\%}\) where 
-\(\mathrm{P}\bigl(X < \chi_{5\%}\bigr) =\!= 5\%\),
+$BR $SPACE $SPACE $SPACE ${BTT}qchisq\((1-.05,\;9)\)${ETT} $BR
+computes the critical value \({\large \chi}_{5\%}\) where 
+\(\mathrm{P}\bigl(X \ge {\large \chi}_{5\%}\bigr) =\!= 5\%\),
 and \(X\) has 9 degrees of freedom.
+EOF
+\}
 
+$PAR
+$HR
+$PAR
+Click below to open an embedded R-window which you can use to check your 
+code or perform computations
 
 END_TEXT
+Scaffold::Begin(can_open=>"always",is_open=>"never");
+########################################################
+Section::Begin("$BBOLD Embedded R Window $EBOLD");
+
+BEGIN_TEXT
+
+${BCENTER}
+$Rframe
+${ECENTER}
+
+END_TEXT
+
+Section::End();
+########################################################
+Scaffold::End();
 
 Context()->normalStrings;
 
diff --git a/Contrib/METU-NCC/Statistics/S3_CI/CI_z.pg b/Contrib/METU-NCC/Statistics/S3_CI/CI_z.pg
index b7d9c52b7a..c0940dab02 100644
--- a/Contrib/METU-NCC/Statistics/S3_CI/CI_z.pg
+++ b/Contrib/METU-NCC/Statistics/S3_CI/CI_z.pg
@@ -18,14 +18,14 @@
 DOCUMENT();
 
 loadMacros(
-   "PGstandard.pl",     # Standard macros for PG language
-   "MathObjects.pl",
-   "contextArbitraryString.pl",
-   "RserveClient.pl",
-   "PGcourse.pl",
+	"PGstandard.pl",     # Standard macros for PG language
+	"MathObjects.pl",
+	"contextArbitraryString.pl",
+	"RserveClient.pl",
+	"PGcourse.pl",
+	"scaffold.pl"
 );
 
-# Print problem number and point value (weight) for the problem
 TEXT(beginproblem());
 
 COMMENT('Requires integrated R server (Rserve.pm)');
@@ -96,27 +96,42 @@ $BR
 
 $PAR
 
-$PAR
-$HR
-$PAR
-You may use the embedded R window below to check your code and perform computations.$BR
-${BCENTER}
-$Rframe
-${ECENTER}
-$PAR
+\{ knowlLink("(Reminder about R commands.)", value=> <<EOF);
 Recall that if \(Z\sim \mathrm{Normal}(0,1)\) 
 then the critical values of \(Z\) are computed in R by the command:
 $BR
 \(\qquad z_\alpha \  =\!= \   \) 
-    ${BTT}\(-\)qnorm(\(\alpha\))${ETT}
+    ${BTT}qnorm(\(1-\alpha\))${ETT}
 $BR
 For example 
-$BR $SPACE $SPACE $SPACE ${BTT}\(-\)qnorm\((.05)\)${ETT} $SPACE $SPACE $SPACE 
+$BR $SPACE $SPACE $SPACE ${BTT}qnorm\((1-.05)\)${ETT} $BR
 computes the critical value \(z_{5\%}\) where 
-\(\mathrm{P}\bigl(Z > z_{5\%}\bigr) =\!= 5\%\).
+\(\mathrm{P}\bigl(Z \ge z_{5\%}\bigr) =\!= 5\%\).
+EOF
+\}
 
+$PAR
+$HR
+$PAR
+Click below to open an embedded R-window which you can use to check your 
+code or perform computations
 
 END_TEXT
+Scaffold::Begin(can_open=>"always",is_open=>"never");
+########################################################
+Section::Begin("$BBOLD Embedded R Window $EBOLD");
+
+BEGIN_TEXT
+
+${BCENTER}
+$Rframe
+${ECENTER}
+
+END_TEXT
+
+Section::End();
+########################################################
+Scaffold::End();
 
 Context()->normalStrings;