function x = gauss(A, b)
    [r,n] = size(A);
    x = zeros(size(b));
    A = [A,b]
    for i = 1:n
      [v, p] = max(abs(A(i:n, i)));
      p = p + i - 1;
      A([i p],:) = A([p i],:);
      for j = i+1:n
        coeff = A(j, i)/ A(i,i);
        A(j, i:n+1) = A(j, i:n+1) - coeff * A(i,i:n+1)
      endfor
    endfor
    x = backsub(A(:,1:n),A(:,n+1));
end;