[linalg.algs.blas1.iamax] Fix return type of vector_idx_abs_max

The declarations use extents_type (a std::extents shape type), but the
Returns clause specifies a scalar index of type size_type. Replace
extents_type with size_type in [linalg.syn] and [linalg.algs.blas1.iamax].

Author: abhinavagarwal07

source/numerics.tex

@@ -11143,9 +11143,9 @@
 
   // \ref{linalg.algs.blas1.iamax}, index of maximum absolute value of vector elements
   template<@\exposconcept{in-vector}@ InVec>
-    typename InVec::extents_type vector_idx_abs_max(InVec v);
+    typename InVec::size_type vector_idx_abs_max(InVec v);
   template<class ExecutionPolicy, @\exposconcept{in-vector}@ InVec>
-    typename InVec::extents_type vector_idx_abs_max(ExecutionPolicy&& exec, InVec v);
+    typename InVec::size_type vector_idx_abs_max(ExecutionPolicy&& exec, InVec v);
 
   // \ref{linalg.algs.blas1.matfrobnorm}, Frobenius norm of a matrix
   template<@\exposconcept{in-matrix}@ InMat, @\exposconcept{scalar}@ Scalar>
@@ -13980,9 +13980,9 @@
 \indexlibraryglobal{vector_idx_abs_max}%
 \begin{itemdecl}
 template<@\exposconcept{in-vector}@ InVec>
-  typename InVec::extents_type vector_idx_abs_max(InVec v);
+  typename InVec::size_type vector_idx_abs_max(InVec v);
 template<class ExecutionPolicy, @\exposconcept{in-vector}@ InVec>
-  typename InVec::extents_type vector_idx_abs_max(ExecutionPolicy&& exec, InVec v);
+  typename InVec::size_type vector_idx_abs_max(ExecutionPolicy&& exec, InVec v);
 \end{itemdecl}
 
 \begin{itemdescr}