% Question3b

A = [ 1,2,3; 4,5,6; 1,0,50 ]

% do the gaussian elimination
% Note that gauss uses a copy of A

[Aupper,r] = luFactor(A)

% Solve 3 systems

e1 = [1,0,0]'
e2 = [0,1,0]'
e3 = [0,0,1]'
x1 = luSolve(Aupper,r,e1)
x2 = luSolve(Aupper,r,e2)
x3 = luSolve(Aupper,r,e3)

% check inverse with the matlab inv function

Ainv = [x1,x2,x3]
AinvCheck = inv(A)