s to use x=A\b.  The residual r is a vector of what's left
% over in each equation, and its norm tells you how accurately the system
% was solved.

format compact ;
A = rand (3)
b = rand (3,1)
x = A\b
r = b-A*x ;
norm (r)

%% BACKSLASH versus INV ... let the battle begin
%
% The backslash operation x=A\b is mathematically the same as x=inv(A)*b.
% However, backslash is faster and more accurate since it uses a matrix
% factorization instead of multiplying by the inverse.  Even though your
% linear algebra te