Using rref to give number of solutions (which is either 0, 1 or oo)

The matrix eqn A X = B, gives augmented matrix (A | B) which is turned
into rref form.

0: If the last column has a pivot, the system is not consistent. Another
way of waying this is the rank of the augmented matrix > the rank of the
coefficient matrix

1: If it is consistent and the number of pivots = number of unknowns

oo: If it is consistent and the number of pivots < number of unknowns.

Basically on page 12 of the text.

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Matrix multiplication:
	m x n times n x p producing m x p
	A*B might not = B*A
	A^T (transpose) which is A' in scilab