Linprog to maximise a function

Hello. I think, that I did a mistake in my program for maximize x8. I have a function: fx= -0.818x1 + 0.241x2 + 4.737x3 + 0.2x4 + 0.483x5 - 0.02x6 + 0.06x7 I made restriction for my resulting variable: it cant be more, than 100. And i have some other resrictions, which you can see in my cod. _________________________________________________________________

C = [-0.818 0.241 4.737 0.2 0.483 -0.02 0.06]; 

D = [-0.818 0.241 4.737 0.2 0.483 -0.02 0.06]; 

B = [100];

% Aeq = [1 -1 1];

% beq = [0];

lb = [22 52 3.5 12 105 300 800]; 

ub = [40 80 5.9 22 150 700 1200];

f = C;

A = D;

b = B; 

[x,fval] = linprog(-f,A,b,[],[],lb,ub);

x

fval
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I got the result fval = -100 - is good, but when i change my restrictions - result still 100, only x changes. Maybe it's good, but I don't know it, or it's a code mistake.

Answer 1

[John D'Errico]

You are maximizing f(x), subject to the constraint that f(x) cannot be larger than 100.

There are far too few constraints on x, except that the vector must lie with a rather large hyper-rectangle, and that f(x) must not exceed 100. So you can have a huge (infinite) variety of solutions, all of which will yield exactly 100 for f(x).

Change the bounds, who cares? You can still get f(x) == 100 in a different way. Were you to change the bounds on x by too much, eventually you can end up with a system with no solution at all.

Why is this even remotely surprising? It seems to have worked.

[Ivan]

thanks!