Totally Unimodular

Checks if a matrix is totally unimodular

A matrix is totally unimodular provided all of its square submatrices have determinant 1, -1, or 0. This function checks if a matrix is totally unimodular. If it is not totally unimodular, it also returns the indices of the violating submatrix. This code differs from tum.m (http://www.mathworks.com/matlabcentral/fileexchange/18029-totally-unimodular) by iterating through all submatrices without making a long list of these submatrices, thus avoiding matlab memory/storage issues.