From b849181deb4fdb92309ea07cd63e4b3ed5d5d4a5 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Fri, 4 Sep 2020 21:02:13 -0400
Subject: [PATCH 01/15] Initial Commit of KS

Simple 1D Chaotic test problem that is significantly better understood than Lorenz '96
---
 .../+kuramotosivashinsky/+presets/Canonical.m | 29 +++++++++++++++++
 .../KuramotoSivashinskyProblem.m              | 32 +++++++++++++++++++
 src/+otp/+kuramotosivashinsky/f.m             |  5 +++
 src/+otp/+kuramotosivashinsky/jac.m           |  5 +++
 4 files changed, 71 insertions(+)
 create mode 100644 src/+otp/+kuramotosivashinsky/+presets/Canonical.m
 create mode 100644 src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
 create mode 100644 src/+otp/+kuramotosivashinsky/f.m
 create mode 100644 src/+otp/+kuramotosivashinsky/jac.m

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
new file mode 100644
index 00000000..430df49b
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -0,0 +1,29 @@
+classdef Canonical < otp.kuramotosivashinsky.KuramotoSivashinskyProblem
+    
+    methods
+        function obj = Canonical(varargin)
+            
+            p = inputParser;
+            addParameter(p, 'Size', 64, @isscalar);
+            addParameter(p, 'L', 25, @isscalar);
+
+            parse(p, varargin{:});
+            
+            s = p.Results;
+            
+            n = s.Size;
+            
+            
+            params.n = n;
+            params.l = s.L;
+            
+            x = linspace(0, 10*pi, n + 1);
+            
+            u0 = 4*cos(x(1:end-1)).';
+
+            tspan = [0, 100];
+            
+            obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0, params);
+        end
+    end
+end
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
new file mode 100644
index 00000000..2e24150e
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -0,0 +1,32 @@
+classdef KuramotoSivashinskyProblem < otp.Problem
+    
+    methods
+        function obj = KuramotoSivashinskyProblem(timeSpan, y0, parameters)
+            obj@otp.Problem('Kuramoto Sivashinsky Problem', [], timeSpan, y0, parameters);
+        end
+    end
+    
+    methods (Access = protected)
+        function onSettingsChanged(obj)
+            n = obj.Parameters.n;
+            l = obj.Parameters.l;
+            
+            domain = [-l, l];
+            D = otp.utils.pde.D(n, domain, 'C');
+            L = otp.utils.pde.laplacian(n, domain, 1, 'C');
+            
+            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, D, L), ...
+                otp.Rhs.FieldNames.Jacobian, @(t, u) otp.kuramotosivashinsky.jac(t, u, D, L));
+            
+        end
+        
+        function validateNewState(obj, newTimeSpan, newY0, newParameters)
+            validateNewState@otp.Problem(obj, ...
+                newTimeSpan, newY0, newParameters)
+            
+            otp.utils.StructParser(newParameters) ...
+                .checkField('n', 'scalar', 'integer', 'finite', 'positive') ...
+                .checkField('l', 'scalar', 'integer', 'finite', 'positive');
+        end
+    end
+end
diff --git a/src/+otp/+kuramotosivashinsky/f.m b/src/+otp/+kuramotosivashinsky/f.m
new file mode 100644
index 00000000..15f328d2
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/f.m
@@ -0,0 +1,5 @@
+function du = f(~, u, D, L)
+
+du = - L*(L*u + u) - u.*(D*u);
+
+end
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
new file mode 100644
index 00000000..aaf9b104
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -0,0 +1,5 @@
+function j = jac(~, u, D, L)
+
+j = -L*L - L - spdiags(u, 0, numel(u), numel(u))*D - spdiags(D*u, 0, numel(u), numel(u));
+
+end

From c7beadc9e2cde6220682b4be9215f06ef0ab65e1 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Tue, 8 Sep 2020 20:35:57 -0400
Subject: [PATCH 02/15] Completely changed the problem to be spectral

---
 .../+kuramotosivashinsky/+presets/Canonical.m | 20 ++++----
 .../KuramotoSivashinskyProblem.m              | 46 +++++++++++++++----
 src/+otp/+kuramotosivashinsky/f.m             |  6 ++-
 src/+otp/+kuramotosivashinsky/jac.m           |  4 +-
 src/+otp/+kuramotosivashinsky/jvp.m           |  5 ++
 5 files changed, 59 insertions(+), 22 deletions(-)
 create mode 100644 src/+otp/+kuramotosivashinsky/jvp.m

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index 430df49b..8f54369c 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -4,26 +4,30 @@
         function obj = Canonical(varargin)
             
             p = inputParser;
-            addParameter(p, 'Size', 64, @isscalar);
-            addParameter(p, 'L', 25, @isscalar);
+            addParameter(p, 'Size', 128);
+            addParameter(p, 'L', 32*pi);
 
             parse(p, varargin{:});
             
             s = p.Results;
             
-            n = s.Size;
+            N = s.Size;
+            L = s.L;
             
+            params.L = L;
             
-            params.n = n;
-            params.l = s.L;
+            h=L/N;
             
-            x = linspace(0, 10*pi, n + 1);
+            x=h*(1:N).';
             
-            u0 = 4*cos(x(1:end-1)).';
+            u0 = cos(x/16).*(1+sin(x/16));
+            
+            u0hat = fft(u0);
 
             tspan = [0, 100];
             
-            obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0, params);
+            obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
+            
         end
     end
 end
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index 2e24150e..521d2f54 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -2,31 +2,57 @@
     
     methods
         function obj = KuramotoSivashinskyProblem(timeSpan, y0, parameters)
-            obj@otp.Problem('Kuramoto Sivashinsky Problem', [], timeSpan, y0, parameters);
+            obj@otp.Problem('Kuramoto-Sivashinsky', [], timeSpan, y0, parameters);
         end
     end
     
+    methods
+        function soly = solution2real(soly)
+            
+            if isstruct(soly)
+                soly.y = real(ifft(soly.y));
+            else
+                soly = real(ifft(soly.')).';
+            end
+            
+        end
+        
+    end
+    
     methods (Access = protected)
         function onSettingsChanged(obj)
-            n = obj.Parameters.n;
-            l = obj.Parameters.l;
             
-            domain = [-l, l];
-            D = otp.utils.pde.D(n, domain, 'C');
-            L = otp.utils.pde.laplacian(n, domain, 1, 'C');
+            L = obj.Parameters.L;
             
-            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, D, L), ...
-                otp.Rhs.FieldNames.Jacobian, @(t, u) otp.kuramotosivashinsky.jac(t, u, D, L));
+            N = numel(obj.Y0);
+            
+            div = L/(2*pi);
+            
+            k = (1i*[0:(N/2 - 1), 0, (-N/2 + 1):-1].'/div);
+            k2 = k.^2;
+            k4 = k.^4;
+            
+            Dfft = dftmtx(N);
+            Difft = conj(Dfft)/N;
+
+            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, k, k2, k4), ...
+                otp.Rhs.FieldNames.Jacobian, ...
+                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4, Dfft, Difft), ...
+                otp.Rhs.FieldNames.JacobianVectorProduct, ...
+                @(t, u, v) otp.kuramotosivashinsky.jvp(t,u, k, k2, k4, v));
             
         end
         
         function validateNewState(obj, newTimeSpan, newY0, newParameters)
+            
             validateNewState@otp.Problem(obj, ...
                 newTimeSpan, newY0, newParameters)
             
+            assert(mod(numel(newY0), 2) == 0);
+            
             otp.utils.StructParser(newParameters) ...
-                .checkField('n', 'scalar', 'integer', 'finite', 'positive') ...
-                .checkField('l', 'scalar', 'integer', 'finite', 'positive');
+                .checkField('L', 'scalar', 'finite', 'positive');
+            
         end
     end
 end
diff --git a/src/+otp/+kuramotosivashinsky/f.m b/src/+otp/+kuramotosivashinsky/f.m
index 15f328d2..1c58fb1c 100644
--- a/src/+otp/+kuramotosivashinsky/f.m
+++ b/src/+otp/+kuramotosivashinsky/f.m
@@ -1,5 +1,7 @@
-function du = f(~, u, D, L)
+function ut = f(~, u, k, k2, k4)
 
-du = - L*(L*u + u) - u.*(D*u);
+u2 = fft(real(ifft(u)).^2);
+
+ut = - k2.*u - k4.*u -(k/2).*u2;
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
index aaf9b104..b75bcacf 100644
--- a/src/+otp/+kuramotosivashinsky/jac.m
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -1,5 +1,5 @@
-function j = jac(~, u, D, L)
+function j = jac(~, u, k, k2, k4, Dfft, Difft)
 
-j = -L*L - L - spdiags(u, 0, numel(u), numel(u))*D - spdiags(D*u, 0, numel(u), numel(u));
+j = -diag(k2) - diag(k4) - diag(k)*Dfft*diag(ifft(u))*Difft;
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jvp.m b/src/+otp/+kuramotosivashinsky/jvp.m
new file mode 100644
index 00000000..f340ed33
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/jvp.m
@@ -0,0 +1,5 @@
+function jv = jvp(~, u, k, k2, k4, v)
+
+jv = -k2.*v - k4.*v - k.*fft(real(ifft(u)).*real(ifft(v)));
+
+end

From e2f3c6a008dffe5d185e010c1577e6ecb22f7255 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Tue, 8 Sep 2020 22:44:32 -0400
Subject: [PATCH 03/15] Made jacobian more optimal; other

Note: the jacobian is dense for all non-trivial inputs. for the initial condition it might seem like the jacobian is sparse, but this is a red herring. The jacobian is dense, and the way in which it is computed in this code is as efficient as I dare make it.
---
 src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m | 7 ++-----
 src/+otp/+kuramotosivashinsky/jac.m                        | 4 ++--
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index 521d2f54..bed9637d 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -24,20 +24,17 @@ function onSettingsChanged(obj)
             
             L = obj.Parameters.L;
             
-            N = numel(obj.Y0);
+            N = obj.NumVars;
             
             div = L/(2*pi);
             
             k = (1i*[0:(N/2 - 1), 0, (-N/2 + 1):-1].'/div);
             k2 = k.^2;
             k4 = k.^4;
-            
-            Dfft = dftmtx(N);
-            Difft = conj(Dfft)/N;
 
             obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, k, k2, k4), ...
                 otp.Rhs.FieldNames.Jacobian, ...
-                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4, Dfft, Difft), ...
+                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4), ...
                 otp.Rhs.FieldNames.JacobianVectorProduct, ...
                 @(t, u, v) otp.kuramotosivashinsky.jvp(t,u, k, k2, k4, v));
             
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
index b75bcacf..8be8bc71 100644
--- a/src/+otp/+kuramotosivashinsky/jac.m
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -1,5 +1,5 @@
-function j = jac(~, u, k, k2, k4, Dfft, Difft)
+function j = jac(~, u, k, k2, k4)
 
-j = -diag(k2) - diag(k4) - diag(k)*Dfft*diag(ifft(u))*Difft;
+j = -diag(k2) - diag(k4) - diag(k)*ifft(fft(diag(ifft(u))).').';
 
 end

From dd2f38af2d1167efa171fd723fdd3603ee5a0cbf Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Wed, 9 Sep 2020 11:08:48 -0400
Subject: [PATCH 04/15] Added Jacobian Adjoint (conjugate as well) vector
 product.

---
 src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m | 4 +++-
 src/+otp/+kuramotosivashinsky/javp.m                       | 5 +++++
 src/+otp/+kuramotosivashinsky/jvp.m                        | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 src/+otp/+kuramotosivashinsky/javp.m

diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index bed9637d..61c00aee 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -36,7 +36,9 @@ function onSettingsChanged(obj)
                 otp.Rhs.FieldNames.Jacobian, ...
                 @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4), ...
                 otp.Rhs.FieldNames.JacobianVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.jvp(t,u, k, k2, k4, v));
+                @(t, u, v) otp.kuramotosivashinsky.jvp(t,u, k, k2, k4, v), ...
+                otp.Rhs.FieldNames.JacobianAdjointVectorProduct, ...
+                @(t, u, v) otp.kuramotosivashinsky.javp(t,u, k, k2, k4, v));
             
         end
         
diff --git a/src/+otp/+kuramotosivashinsky/javp.m b/src/+otp/+kuramotosivashinsky/javp.m
new file mode 100644
index 00000000..05577830
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/javp.m
@@ -0,0 +1,5 @@
+function jv = javp(~, u, k, k2, k4, v)
+
+jv = -k2.*v - k4.*v - fft(real(ifft(u)).*ifft(conj(k).*v));
+
+end
diff --git a/src/+otp/+kuramotosivashinsky/jvp.m b/src/+otp/+kuramotosivashinsky/jvp.m
index f340ed33..da28a3d8 100644
--- a/src/+otp/+kuramotosivashinsky/jvp.m
+++ b/src/+otp/+kuramotosivashinsky/jvp.m
@@ -1,5 +1,5 @@
 function jv = jvp(~, u, k, k2, k4, v)
 
-jv = -k2.*v - k4.*v - k.*fft(real(ifft(u)).*real(ifft(v)));
+jv = -k2.*v - k4.*v - k.*fft(real(ifft(u)).*ifft(v));
 
 end

From 09e0966e088f80f0ed27c1d183a9fed276a00dec Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Wed, 9 Sep 2020 13:05:21 -0400
Subject: [PATCH 05/15] added citation and fixed the tspan

---
 .../+kuramotosivashinsky/+presets/Canonical.m | 20 ++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index 8f54369c..a56b80a8 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -1,3 +1,17 @@
+% The Kuramoto-Sivashinky equation is a chaotic problem.
+%
+% In this particular discretization, we are applying a spectral
+% method, therefore the boundary conditions will be chosen to be as cyclic
+% on the domain [0, L]. Note that this is different from another typical
+% domain of [-L, L]. The larger the L, the more interesting the problem is
+% but the more points are required to do a good discretization. The current
+% canonical implementation with the size, L, and  is used in
+%
+% Kassam, Aly-Khan, and Lloyd N. Trefethen. 
+% "Fourth-order time-stepping for stiff PDEs." 
+% SIAM Journal on Scientific Computing 26, no. 4 (2005): 1214-1233.
+%
+
 classdef Canonical < otp.kuramotosivashinsky.KuramotoSivashinskyProblem
     
     methods
@@ -16,15 +30,15 @@
             
             params.L = L;
             
-            h=L/N;
+            h = L/N;
             
-            x=h*(1:N).';
+            x = h*(1:N).';
             
             u0 = cos(x/16).*(1+sin(x/16));
             
             u0hat = fft(u0);
 
-            tspan = [0, 100];
+            tspan = [0, 150];
             
             obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
             

From 7e63fe29a33be0e486e2136879e334757d45b671 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Wed, 9 Sep 2020 15:56:25 -0400
Subject: [PATCH 06/15] applied fixes

---
 src/+otp/+kuramotosivashinsky/+presets/Canonical.m        | 4 +++-
 .../+kuramotosivashinsky/KuramotoSivashinskyProblem.m     | 8 +++++---
 src/+otp/+kuramotosivashinsky/javp.m                      | 2 +-
 src/+otp/+kuramotosivashinsky/jvp.m                       | 2 +-
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index a56b80a8..6e993ccb 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -32,7 +32,9 @@
             
             h = L/N;
             
-            x = h*(1:N).';
+            % exclude the left boundary point as it is identical to the
+            % right boundary point
+            x = linspace(h, L, N).';
             
             u0 = cos(x/16).*(1+sin(x/16));
             
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index 61c00aee..a18d8a45 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -36,9 +36,9 @@ function onSettingsChanged(obj)
                 otp.Rhs.FieldNames.Jacobian, ...
                 @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4), ...
                 otp.Rhs.FieldNames.JacobianVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.jvp(t,u, k, k2, k4, v), ...
+                @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, k, k2, k4), ...
                 otp.Rhs.FieldNames.JacobianAdjointVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.javp(t,u, k, k2, k4, v));
+                @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, k, k2, k4));
             
         end
         
@@ -47,7 +47,9 @@ function validateNewState(obj, newTimeSpan, newY0, newParameters)
             validateNewState@otp.Problem(obj, ...
                 newTimeSpan, newY0, newParameters)
             
-            assert(mod(numel(newY0), 2) == 0);
+            if mod(numel(newY0), 2) ~= 0
+                error('The problem size has to be an even integer.');
+            end
             
             otp.utils.StructParser(newParameters) ...
                 .checkField('L', 'scalar', 'finite', 'positive');
diff --git a/src/+otp/+kuramotosivashinsky/javp.m b/src/+otp/+kuramotosivashinsky/javp.m
index 05577830..e26d9b10 100644
--- a/src/+otp/+kuramotosivashinsky/javp.m
+++ b/src/+otp/+kuramotosivashinsky/javp.m
@@ -1,4 +1,4 @@
-function jv = javp(~, u, k, k2, k4, v)
+function jv = javp(~, u, v, k, k2, k4)
 
 jv = -k2.*v - k4.*v - fft(real(ifft(u)).*ifft(conj(k).*v));
 
diff --git a/src/+otp/+kuramotosivashinsky/jvp.m b/src/+otp/+kuramotosivashinsky/jvp.m
index da28a3d8..c208d029 100644
--- a/src/+otp/+kuramotosivashinsky/jvp.m
+++ b/src/+otp/+kuramotosivashinsky/jvp.m
@@ -1,4 +1,4 @@
-function jv = jvp(~, u, k, k2, k4, v)
+function jv = jvp(~, u, v, k, k2, k4)
 
 jv = -k2.*v - k4.*v - k.*fft(real(ifft(u)).*ifft(v));
 

From 91d439c8d5691993f606cb279b34400cecf7a923 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Thu, 8 Jul 2021 15:59:01 -0400
Subject: [PATCH 07/15] Steven's changes all implemented.

---
 .../+kuramotosivashinsky/KuramotoSivashinskyProblem.m | 11 ++++++-----
 src/+otp/+kuramotosivashinsky/f.m                     |  4 ++--
 src/+otp/+kuramotosivashinsky/jac.m                   |  4 ++--
 src/+otp/+kuramotosivashinsky/javp.m                  |  4 ++--
 src/+otp/+kuramotosivashinsky/jvp.m                   |  4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index a18d8a45..3c1d8686 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -7,7 +7,7 @@
     end
     
     methods
-        function soly = solution2real(soly)
+        function soly = convert2grid(soly)
             
             if isstruct(soly)
                 soly.y = real(ifft(soly.y));
@@ -31,14 +31,15 @@ function onSettingsChanged(obj)
             k = (1i*[0:(N/2 - 1), 0, (-N/2 + 1):-1].'/div);
             k2 = k.^2;
             k4 = k.^4;
+            k24 = k2 + k4;
 
-            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, k, k2, k4), ...
+            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, k, k24), ...
                 otp.Rhs.FieldNames.Jacobian, ...
-                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k2, k4), ...
+                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k24), ...
                 otp.Rhs.FieldNames.JacobianVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, k, k2, k4), ...
+                @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, k, k24), ...
                 otp.Rhs.FieldNames.JacobianAdjointVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, k, k2, k4));
+                @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, k, k24));
             
         end
         
diff --git a/src/+otp/+kuramotosivashinsky/f.m b/src/+otp/+kuramotosivashinsky/f.m
index 1c58fb1c..bcd01ce3 100644
--- a/src/+otp/+kuramotosivashinsky/f.m
+++ b/src/+otp/+kuramotosivashinsky/f.m
@@ -1,7 +1,7 @@
-function ut = f(~, u, k, k2, k4)
+function ut = f(~, u, k, k24)
 
 u2 = fft(real(ifft(u)).^2);
 
-ut = - k2.*u - k4.*u -(k/2).*u2;
+ut = -k24.*u - (k/2).*u2;
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
index 8be8bc71..df64dada 100644
--- a/src/+otp/+kuramotosivashinsky/jac.m
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -1,5 +1,5 @@
-function j = jac(~, u, k, k2, k4)
+function j = jac(~, u, k, k24)
 
-j = -diag(k2) - diag(k4) - diag(k)*ifft(fft(diag(ifft(u))).').';
+j = -diag(k24) - k.*ifft(fft(diag(ifft(u))).').';
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/javp.m b/src/+otp/+kuramotosivashinsky/javp.m
index e26d9b10..141f7574 100644
--- a/src/+otp/+kuramotosivashinsky/javp.m
+++ b/src/+otp/+kuramotosivashinsky/javp.m
@@ -1,5 +1,5 @@
-function jv = javp(~, u, v, k, k2, k4)
+function jv = javp(~, u, v, k, k24)
 
-jv = -k2.*v - k4.*v - fft(real(ifft(u)).*ifft(conj(k).*v));
+jv = -k24.*v - fft(real(ifft(u)).*ifft(conj(k).*v));
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jvp.m b/src/+otp/+kuramotosivashinsky/jvp.m
index c208d029..9e01ff41 100644
--- a/src/+otp/+kuramotosivashinsky/jvp.m
+++ b/src/+otp/+kuramotosivashinsky/jvp.m
@@ -1,5 +1,5 @@
-function jv = jvp(~, u, v, k, k2, k4)
+function jv = jvp(~, u, v, k, k24)
 
-jv = -k2.*v - k4.*v - k.*fft(real(ifft(u)).*ifft(v));
+jv = -k24.*v - k.*fft(real(ifft(u)).*ifft(v));
 
 end

From 9a8a63c3e8967c7dfb8e536d34456bff8d2636da Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Thu, 8 Jul 2021 18:00:11 -0400
Subject: [PATCH 08/15] more of steven's fixes

---
 .../+kuramotosivashinsky/KuramotoSivashinskyProblem.m     | 8 ++------
 src/+otp/+kuramotosivashinsky/jac.m                       | 2 +-
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index 3c1d8686..e6d4f2a6 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -7,13 +7,9 @@
     end
     
     methods
-        function soly = convert2grid(soly)
+        function soly = convert2grid(~, soly)
             
-            if isstruct(soly)
-                soly.y = real(ifft(soly.y));
-            else
-                soly = real(ifft(soly.')).';
-            end
+            soly = real(ifft(soly));
             
         end
         
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
index df64dada..08b6a47e 100644
--- a/src/+otp/+kuramotosivashinsky/jac.m
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -1,5 +1,5 @@
 function j = jac(~, u, k, k24)
 
-j = -diag(k24) - k.*ifft(fft(diag(ifft(u))).').';
+j = -diag(k24) - k.*ifft(fft(diag(real(ifft(u)))).').';
 
 end

From 3eb99cd86b4b9c17d3c5b406de6da3c3f08c892b Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Thu, 8 Jul 2021 18:01:11 -0400
Subject: [PATCH 09/15] added a comment for future idiot me

---
 src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index e6d4f2a6..ea45f664 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -24,6 +24,7 @@ function onSettingsChanged(obj)
             
             div = L/(2*pi);
             
+            % note that k already has "i" in it
             k = (1i*[0:(N/2 - 1), 0, (-N/2 + 1):-1].'/div);
             k2 = k.^2;
             k4 = k.^4;

From c1bf87ef9bc7e97e3ee1450d992738bd0b772564 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Thu, 8 Jul 2021 19:03:27 -0400
Subject: [PATCH 10/15] Change initial condition to always be periodic.

---
 src/+otp/+kuramotosivashinsky/+presets/Canonical.m | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index 6e993ccb..e84a6147 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -36,7 +36,7 @@
             % right boundary point
             x = linspace(h, L, N).';
             
-            u0 = cos(x/16).*(1+sin(x/16));
+            u0 = cospi(2*x/L).*(1+sinpi(2*x/L));
             
             u0hat = fft(u0);
 

From 1b53abc4b0b19779860af8829665d19835a95477 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Mon, 12 Jul 2021 10:53:17 -0400
Subject: [PATCH 11/15] Added the preset from Sol ODES2

---
 .../+presets/HairerWanner.m                   | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m

diff --git a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
new file mode 100644
index 00000000..414a1e30
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
@@ -0,0 +1,40 @@
+classdef HairerWanner < otp.kuramotosivashinsky.KuramotoSivashinskyProblem
+    
+    methods
+        function obj = HairerWanner(varargin)
+            
+            p = inputParser;
+            addParameter(p, 'Size', 128);
+            addParameter(p, 'L', 80*pi);
+
+            parse(p, varargin{:});
+            
+            s = p.Results;
+            
+            N = s.Size;
+            L = s.L;
+            
+            params.L = L;
+            
+            h = L/N;
+            
+            % exclude the left boundary point as it is identical to the
+            % right boundary point
+            x = linspace(h, L, N).';
+            
+            eta1 = min(x/L, 0.1 - x/L);
+            eta2 = 20*(x/L - 0.2).*(0.3 - x/L);
+            eta3 = min(x/L - 0.6, 0.7 - x/L);
+            eta4 = min(x/L - 0.9, 1 - x/L);
+            
+            u0 = 16*max(0, max(eta1, max(eta2, max(eta3, eta4))));
+            
+            u0hat = fft(u0);
+
+            tspan = [0, 150];
+            
+            obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
+            
+        end
+    end
+end

From 33b0987156a495577ee06b3b16fb37b800832e31 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Mon, 12 Jul 2021 11:56:51 -0400
Subject: [PATCH 12/15] Minor fix to N

---
 src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
index 414a1e30..7b08608b 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
@@ -4,7 +4,7 @@
         function obj = HairerWanner(varargin)
             
             p = inputParser;
-            addParameter(p, 'Size', 128);
+            addParameter(p, 'Size', 1024);
             addParameter(p, 'L', 80*pi);
 
             parse(p, varargin{:});

From 09f0c921ebd8f1d23fe639e07822827c521c711f Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Mon, 12 Jul 2021 12:13:41 -0400
Subject: [PATCH 13/15] tspan fix

---
 src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
index 7b08608b..93824d14 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
@@ -31,7 +31,7 @@
             
             u0hat = fft(u0);
 
-            tspan = [0, 150];
+            tspan = [0, 100];
             
             obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
             

From 8c0e7a3463b0412fe71b33b3d8e3c65f1727176d Mon Sep 17 00:00:00 2001
From: Steven Roberts <sroberts994@gmail.com>
Date: Wed, 28 Jul 2021 20:35:48 -0400
Subject: [PATCH 14/15] Improvements for Jacobian and JAVP

---
 .../+kuramotosivashinsky/+presets/Canonical.m | 14 ++++-------
 .../+presets/HairerWanner.m                   | 12 ++++------
 .../KuramotoSivashinskyProblem.m              | 24 +++++++------------
 src/+otp/+kuramotosivashinsky/f.m             |  6 ++---
 src/+otp/+kuramotosivashinsky/jac.m           |  5 ++--
 src/+otp/+kuramotosivashinsky/javp.m          |  4 ++--
 src/+otp/+kuramotosivashinsky/jvp.m           |  4 ++--
 7 files changed, 27 insertions(+), 42 deletions(-)

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index e84a6147..7800a0b6 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -7,8 +7,8 @@
 % but the more points are required to do a good discretization. The current
 % canonical implementation with the size, L, and  is used in
 %
-% Kassam, Aly-Khan, and Lloyd N. Trefethen. 
-% "Fourth-order time-stepping for stiff PDEs." 
+% Kassam, Aly-Khan, and Lloyd N. Trefethen.
+% "Fourth-order time-stepping for stiff PDEs."
 % SIAM Journal on Scientific Computing 26, no. 4 (2005): 1214-1233.
 %
 
@@ -20,26 +20,22 @@
             p = inputParser;
             addParameter(p, 'Size', 128);
             addParameter(p, 'L', 32*pi);
-
             parse(p, varargin{:});
             
             s = p.Results;
             
             N = s.Size;
             L = s.L;
-            
             params.L = L;
             
-            h = L/N;
-            
             % exclude the left boundary point as it is identical to the
             % right boundary point
-            x = linspace(h, L, N).';
+            x = linspace(L / N, L, N).';
             
-            u0 = cospi(2*x/L).*(1+sinpi(2*x/L));
+            u0 = cospi(2 * x / L) .* (1 + sinpi(2 * x / L));
             
             u0hat = fft(u0);
-
+            
             tspan = [0, 150];
             
             obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
diff --git a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
index 93824d14..04030db2 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/HairerWanner.m
@@ -5,8 +5,8 @@
             
             p = inputParser;
             addParameter(p, 'Size', 1024);
-            addParameter(p, 'L', 80*pi);
-
+            addParameter(p, 'L', 80 * pi);
+            
             parse(p, varargin{:});
             
             s = p.Results;
@@ -16,21 +16,19 @@
             
             params.L = L;
             
-            h = L/N;
-            
             % exclude the left boundary point as it is identical to the
             % right boundary point
-            x = linspace(h, L, N).';
+            x = linspace(L/N, L, N).';
             
             eta1 = min(x/L, 0.1 - x/L);
             eta2 = 20*(x/L - 0.2).*(0.3 - x/L);
             eta3 = min(x/L - 0.6, 0.7 - x/L);
             eta4 = min(x/L - 0.9, 1 - x/L);
             
-            u0 = 16*max(0, max(eta1, max(eta2, max(eta3, eta4))));
+            u0 = 16*max(0, max([eta1, eta2, eta3, eta4], [], 2));
             
             u0hat = fft(u0);
-
+            
             tspan = [0, 100];
             
             obj = obj@otp.kuramotosivashinsky.KuramotoSivashinskyProblem(tspan, u0hat, params);
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index ea45f664..e9c6ccdb 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -9,7 +9,7 @@
     methods
         function soly = convert2grid(~, soly)
             
-            soly = real(ifft(soly));
+            soly = abs(ifft(soly));
             
         end
         
@@ -17,27 +17,19 @@
     
     methods (Access = protected)
         function onSettingsChanged(obj)
-            
-            L = obj.Parameters.L;
-            
             N = obj.NumVars;
             
-            div = L/(2*pi);
+            k = 2 * pi * [0:(N/2 - 1), 0, (-N/2 + 1):-1].' / obj.Parameters.L;
+            ik = 1i * k;
+            k24 = k.^2 - k.^4;
             
-            % note that k already has "i" in it
-            k = (1i*[0:(N/2 - 1), 0, (-N/2 + 1):-1].'/div);
-            k2 = k.^2;
-            k4 = k.^4;
-            k24 = k2 + k4;
-
-            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, k, k24), ...
+            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, ik, k24), ...
                 otp.Rhs.FieldNames.Jacobian, ...
-                @(t, u) otp.kuramotosivashinsky.jac(t,u, k, k24), ...
+                @(t, u) otp.kuramotosivashinsky.jac(t,u, ik, k24), ...
                 otp.Rhs.FieldNames.JacobianVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, k, k24), ...
+                @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, ik, k24), ...
                 otp.Rhs.FieldNames.JacobianAdjointVectorProduct, ...
-                @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, k, k24));
-            
+                @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, ik, k24));
         end
         
         function validateNewState(obj, newTimeSpan, newY0, newParameters)
diff --git a/src/+otp/+kuramotosivashinsky/f.m b/src/+otp/+kuramotosivashinsky/f.m
index bcd01ce3..2aeb2721 100644
--- a/src/+otp/+kuramotosivashinsky/f.m
+++ b/src/+otp/+kuramotosivashinsky/f.m
@@ -1,7 +1,5 @@
-function ut = f(~, u, k, k24)
+function ut = f(~, u, ik, k24)
 
-u2 = fft(real(ifft(u)).^2);
-
-ut = -k24.*u - (k/2).*u2;
+ut = k24 .* u - (ik/2) .* fft(ifft(u).^2);
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jac.m b/src/+otp/+kuramotosivashinsky/jac.m
index 08b6a47e..0a0532c2 100644
--- a/src/+otp/+kuramotosivashinsky/jac.m
+++ b/src/+otp/+kuramotosivashinsky/jac.m
@@ -1,5 +1,6 @@
-function j = jac(~, u, k, k24)
+function j = jac(~, u, ik, k24)
 
-j = -diag(k24) - k.*ifft(fft(diag(real(ifft(u)))).').';
+circulantU = toeplitz(u, [u(1); flipud(u(2:end))]);
+j = diag(k24) - ik / length(u) .* circulantU;
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/javp.m b/src/+otp/+kuramotosivashinsky/javp.m
index 141f7574..62145033 100644
--- a/src/+otp/+kuramotosivashinsky/javp.m
+++ b/src/+otp/+kuramotosivashinsky/javp.m
@@ -1,5 +1,5 @@
-function jv = javp(~, u, v, k, k24)
+function jv = javp(~, u, v, ik, k24)
 
-jv = -k24.*v - fft(real(ifft(u)).*ifft(conj(k).*v));
+jv = k24 .* v + fft(conj(ifft(u)) .* ifft(ik .* v));
 
 end
diff --git a/src/+otp/+kuramotosivashinsky/jvp.m b/src/+otp/+kuramotosivashinsky/jvp.m
index 9e01ff41..995bbac3 100644
--- a/src/+otp/+kuramotosivashinsky/jvp.m
+++ b/src/+otp/+kuramotosivashinsky/jvp.m
@@ -1,5 +1,5 @@
-function jv = jvp(~, u, v, k, k24)
+function jv = jvp(~, u, v, ik, k24)
 
-jv = -k24.*v - k.*fft(real(ifft(u)).*ifft(v));
+jv = k24 .* v - ik .* fft(ifft(u) .* ifft(v));
 
 end

From f9af33c5177731e7b0ac669582843811424cfea6 Mon Sep 17 00:00:00 2001
From: Andrey A Popov <apopov@vt.edu>
Date: Mon, 8 May 2023 13:22:34 -0500
Subject: [PATCH 15/15] Updated for new format, and validated all derivatives.

---
 .../+kuramotosivashinsky/+presets/Canonical.m | 28 +++++++++----------
 .../KuramotoSivashinskyParameters.m           |  7 +++++
 .../KuramotoSivashinskyProblem.m              | 25 +++--------------
 3 files changed, 25 insertions(+), 35 deletions(-)
 create mode 100644 src/+otp/+kuramotosivashinsky/KuramotoSivashinskyParameters.m

diff --git a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
index 7800a0b6..1117e61f 100644
--- a/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
+++ b/src/+otp/+kuramotosivashinsky/+presets/Canonical.m
@@ -1,18 +1,17 @@
-% The Kuramoto-Sivashinky equation is a chaotic problem.
-%
-% In this particular discretization, we are applying a spectral
-% method, therefore the boundary conditions will be chosen to be as cyclic
-% on the domain [0, L]. Note that this is different from another typical
-% domain of [-L, L]. The larger the L, the more interesting the problem is
-% but the more points are required to do a good discretization. The current
-% canonical implementation with the size, L, and  is used in
-%
-% Kassam, Aly-Khan, and Lloyd N. Trefethen.
-% "Fourth-order time-stepping for stiff PDEs."
-% SIAM Journal on Scientific Computing 26, no. 4 (2005): 1214-1233.
-%
-
 classdef Canonical < otp.kuramotosivashinsky.KuramotoSivashinskyProblem
+    % The Kuramoto-Sivashinky equation is a chaotic problem.
+    %
+    % In this particular discretization, we are applying a spectral
+    % method, therefore the boundary conditions will be chosen to be as cyclic
+    % on the domain [0, L]. Note that this is different from another typical
+    % domain of [-L, L]. The larger the L, the more interesting the problem is
+    % but the more points are required to do a good discretization. The current
+    % canonical implementation with the size, L, and  is used in
+    %
+    % Kassam, Aly-Khan, and Lloyd N. Trefethen.
+    % "Fourth-order time-stepping for stiff PDEs."
+    % SIAM Journal on Scientific Computing 26, no. 4 (2005): 1214-1233.
+    %
     
     methods
         function obj = Canonical(varargin)
@@ -26,6 +25,7 @@
             
             N = s.Size;
             L = s.L;
+            params = otp.kuramotosivashinsky.KuramotoSivashinskyParameters;
             params.L = L;
             
             % exclude the left boundary point as it is identical to the
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyParameters.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyParameters.m
new file mode 100644
index 00000000..357f0140
--- /dev/null
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyParameters.m
@@ -0,0 +1,7 @@
+classdef KuramotoSivashinskyParameters
+    % Parameters for the Kuramoto Sivashinsky problem
+    properties
+        % Represents the length-scale of the problem
+        L
+    end
+end
diff --git a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
index e9c6ccdb..39d9c53d 100644
--- a/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
+++ b/src/+otp/+kuramotosivashinsky/KuramotoSivashinskyProblem.m
@@ -8,11 +8,8 @@
     
     methods
         function soly = convert2grid(~, soly)
-            
             soly = abs(ifft(soly));
-            
         end
-        
     end
     
     methods (Access = protected)
@@ -23,27 +20,13 @@ function onSettingsChanged(obj)
             ik = 1i * k;
             k24 = k.^2 - k.^4;
             
-            obj.Rhs = otp.Rhs(@(t, u) otp.kuramotosivashinsky.f(t, u, ik, k24), ...
-                otp.Rhs.FieldNames.Jacobian, ...
+            obj.RHS = otp.RHS(@(t, u) otp.kuramotosivashinsky.f(t, u, ik, k24), ...
+                'Jacobian', ...
                 @(t, u) otp.kuramotosivashinsky.jac(t,u, ik, k24), ...
-                otp.Rhs.FieldNames.JacobianVectorProduct, ...
+                'JacobianVectorProduct', ...
                 @(t, u, v) otp.kuramotosivashinsky.jvp(t, u, v, ik, k24), ...
-                otp.Rhs.FieldNames.JacobianAdjointVectorProduct, ...
+                'JacobianAdjointVectorProduct', ...
                 @(t, u, v) otp.kuramotosivashinsky.javp(t, u, v, ik, k24));
         end
-        
-        function validateNewState(obj, newTimeSpan, newY0, newParameters)
-            
-            validateNewState@otp.Problem(obj, ...
-                newTimeSpan, newY0, newParameters)
-            
-            if mod(numel(newY0), 2) ~= 0
-                error('The problem size has to be an even integer.');
-            end
-            
-            otp.utils.StructParser(newParameters) ...
-                .checkField('L', 'scalar', 'finite', 'positive');
-            
-        end
     end
 end