dccxi

def mtx_inv(M):
    I = mtx_idt(len(M))
    MI = [M[i]+I[i] for i in xrange(len(M))]
    for i in xrange(len(MI)):
        if MI[i][i] == 0:
            temp = M[i]
            M[i] = M[i+1]
            M[i+1] = temp
        if MI[i][i] != 1:
            h = MI[i][i]