% Script gausstest.m

A = [ [3,-13,9,3]; [-6,4,1,-18]; [6,-2,2,4]; [12,-8,6,10] ];
b = [-19; -34; 16; 26];

% Need to save A here
% since gauss returns modified version of A

Asave = A;

[A,r] = gauss(A);

x = gaussSolve(A,r,b);
r
Asave * x - b