Re: [jgap-users] Minimization Problem

[ShankhaB <Sha...@co...>]

Hi 

I also try to solve some simple minimization problem with constraints. As
you already discuss Minimization problem , let me present my case.

 I just want to know is the below mentioned type of problem can be soleved
by JGAP if yes how can I write evaluate () function.
What I understood this is the most important area to justify my problem.

Problem : 

Minimize Z = 2x1+ 8x2   
Subject To -   5x1+x2>=10   
                    2x1+2x2>=14 
                    x1+4x2>=12 
                    x1,x2>=0   and 1<x1<=7    |   0<x2<=4 



What I understand I have to check the my Fitness function or objective
function (Z) in the 

public double evaluate(IChromosome a_subject)  method , where a_subject  is
the one of the potential solution. 

from the "a_subject"  object I have to get the value of X1 and X2 then , I
have to chek all the above mentioned constraints as well as the Fitness
function (Z). 

But HOW this will be determined that for which IChromosome ( a_subject) - Z
will be minimized ? 

Please guide me? 

Thank you, 
shankha 




Guido Garcia Bernardo wrote:
> 
> Hi,
> 
> Could do please elaborate a little on your minimization problem?
> It seems very easy to implement a FitnessFunction with an evaluate
> method that returns better scores as your problem values are lower...
> 
> Something like (not tested) :
> 
> import org.jgap.FitnessFunction;
> import org.jgap.IChromosome;
> 
> public class MyFitness extends FitnessFunction {
>     MyFitness(){
>     }
> 
>     public double evaluate(IChromosome a_subject) {
>         int x = (Integer) a_subject.getGene(0).getAllele();
>         double ret = 1 / x + 1;  // choose your minimization function
>         return ret;
>    }
> }
> 
> Best regards,
> Guido.
> 
> On Mon, Sep 15, 2008 at 10:36 PM, safak <CS...@gc...> wrote:
>>
>> Hi All,
>>
>> How can I write a minimization problem using JGAP?
>>
>> Thanks,
>>
>> SAFAK
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