Why does linprog gives wrong answer?

Hi! My LP problem:

   f=[-7 -5];
   A=[2 3; 2 1; 0 3; 3 0];
   b=[25 20 18 15];
   linprog(f, A, b)

I've got:

ans =
  5.0000
  5.0000

But if I calculate it "by hands" I should've got ans=[5;10]. And my f should be =85 unstead of 60.

Why does it count wrong?

Answer 1

[the cyclist]

I think your hand calculation is incorrect. x1=5 and x2=10 does not obey the first constraint, which requires that 2*x1 + 3*x2 <= 25.

[Titus Edelhofer]

You are right:

x = [5;10];
[A*x b']
ans =
  40    25
  20    20
  30    18
  15    15

In other "words":

A*x<=b'
ans =
   0
   1
   0
   1

Titus