Please help with solver

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asmaa5m3
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Please help with solver

Post by asmaa5m3 » 3 weeks ago

Hello everyone
I created the following program or whatever you call it and compile it with no error, however I got zeros in my z solution
Positive variable x1, x2, x3;
free variable z;

Equations

Con1,
Con2,
Con3,
Obj;

;
Con1.. 75*x1 + 131*x2 + 169*x3 =L= 375;
Con2.. 9*x1 + 15*x2 + 20*x3 =L= 44;
Con3.. 7*x1 + 12*x2 + 15*x3 =L= 34;
Obj.. 0.2*x1 + 0.3*x2+ 0.5*x3 =E= z;

Model Time_minimization /
Con1,
Con2,
Con3,
Obj / ;

options lp = cplex;

Solve Time_minimization Using lp Minimizing z;

Display x1.L, x2.L, x3.L, z.L;


can anyone tell me what's wrong with it????

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Renger
Posts: 245
Joined: 2 years ago

Re: Please help with solver

Post by Renger » 3 weeks ago

Hi
There is nothing wrong with your solution: you have three less-than-or-equal constraints and a to minimize objective equation all with positive coefficients.
This means that {0,0,0} is the minimal and optimal solution. All constraints are met and the objective variable is minimized.
Perhaps you meant greater-than-or-equal in your constraints.

Cheers
Renger

asmaa5m3
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Posts: 3
Joined: 3 weeks ago

Re: Please help with solver

Post by asmaa5m3 » 3 weeks ago

Renger wrote:
3 weeks ago
Hi
There is nothing wrong with your solution: you have three less-than-or-equal constraints and a to minimize objective equation all with positive coefficients.
This means that {0,0,0} is the minimal and optimal solution. All constraints are met and the objective variable is minimized.
Perhaps you meant greater-than-or-equal in your constraints.

Cheers
Renger
thanks for reply first of all
I go zeros for solution, what should I do to get optimal numbers for the three unknowns??

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Renger
Posts: 245
Joined: 2 years ago

Re: Please help with solver

Post by Renger » 3 weeks ago

Hi
This is the optimal solution imagine a one-dimensional problem: x<5 and z=3x. 0 is the optimal solution.
It would make more sense if you would have >= constraints.
Cheers
Renger

asmaa5m3
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Posts: 3
Joined: 3 weeks ago

Re: Please help with solver

Post by asmaa5m3 » 3 weeks ago

Renger wrote:
3 weeks ago
Hi
This is the optimal solution imagine a one-dimensional problem: x<5 and z=3x. 0 is the optimal solution.
It would make more sense if you would have >= constraints.
Cheers
Renger
thanks a lot for helping

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