#U= [2,4,2;0,-1,1;0,0,-1];
#b = [8;0;-1];




#x = backsub(U,b);

A= [2 1 -1 -2; 4 4 1 3; -6 -1 10 10; -2 1 8 4];
b = [2;4;-5;1];

x = gauss(A,b);



n=5

A=5*eye(n) -diag(ones(1,n-1),1)- diag(ones(1,n-1),-1)

b = [4,3* ones(1,n-2),4]'

[L,U,P]= lu(A);

y = forwsub(L,P*b)
x = backsub(U, y)