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Topic: help in genetic algorithm
Replies: 5   Last Post: Apr 8, 2013 4:27 PM

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Alan Weiss

Posts: 1,374
Registered: 11/27/08
Re: help in genetic algorithm
Posted: Apr 8, 2013 12:55 PM
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On 4/8/2013 12:29 PM, mado wrote:
> Alan_Weiss <aweiss@mathworks.com> wrote in message
> <kjudjf$r7m$1@newscl01ah.mathworks.com>...

>> On 4/8/2013 7:02 AM, mado wrote:
>> > i want to ask about genetic algorithm , i am using it to tune pid
>> > parameters but it gives different p, i d values in every running

>> and > it?s not satisfying , need your help
>> > i don't know is this problem of ga parameters or it's the objective
>> > function

>> The genetic algorithm is stochastic, it often gives different results
>> every time.
>> Allow me to suggest that you use patternsearch instead of ga as your
>> solver. It is usually faster, more robust, and easier to tune. The
>> only down side is you need to supply initial points. If you have
>> finite upper and lower bounds, you can try
>> x0 = lb + rand(size(lb)).*(ub - lb);
>> Good luck,

> I need to try ga , i increased generations but don't affect my problem
> is the values is small i need it to be bigger and it should be to
> minimize error being small that mean there is a big error between
> reference and output value

The most important thing to modify is the initial range.

The next most important thing is the population size.

But the best thing to do is chuck ga and use patternsearch.

Alan Weiss
MATLAB mathematical toolbox documentation

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