linear programming in matlab

Dear all

excuse me , i have a problem of linear programming and my problem don't have bound and i'm trying for answer to it but my solution in matlab does not give an accurate answer,

the answer for problem must be as follows:

0.5,0.5,0.5,0.33

can any one help me for it ??

my problem :

MAX = 1 * C-1*D;
 1 * A + 3* B +1 * C <= 2.5;
4 * A +1 * C <= 2.5;
1 * A +3 * B - 0.75 * D <=-0.75+2.5;
4 * A - 0.75*D <=- 0.75+2.5;
1 * A + 1 * B =1;
1* C +1*D <=1;

and my code in matlab is :

f=[0; 0; -1 ; 1]
A=[1   3   1    0 ;
    4   0   1    0;
    1   3   0   -0.75;
    4   0   0   -0.75;
    1   1   0    0;
    0   0   1    1;];

b = [2.5;2.5;1.75;1.75;1;1];
x=linprog(f,A,b)

Thanks so much and Best

Answer 1

[Matt J]

You're clearly missing constraints, if you are supposed to get

 0.5,0.5,0.5,0.33

as an answer.