BasicMatrix
The BasicMatrix concept provides a minimalist interface for
accessing elements from a 2 dimensional table of values.
Refinement of
none
Notation
{M,I,V} 
The matrix, index, and values types that together model the BasicMatrix concept. 
A 
An object of type M. 
i, j 
Objects of type I. 
Associated Types
none
Valid Expressions
A[i][j] 
Returns a reference to the element object stored at index (i,j)
Return type: V& for mutable A or const V&
for constant A.

Complexity guarantees
Element access is constant time.
Concept Checking Class
template <class M, class I, class V>
struct BasicMatrixConcept
{
void constraints() {
V& elt = A[i][j];
const_constraints(A);
ignore_unused_variable_warning(elt);
}
void const_constraints(const M& A) {
const V& elt = A[i][j];
ignore_unused_variable_warning(elt);
}
M A;
I i, j;
};