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Thread Subject:
Function evaluation in GA

Subject: Function evaluation in GA

From: Dua

Date: 15 Jan, 2013 04:44:11

Message: 1 of 3

What is function evaluation in GA? How to relate the values of function evaluations with global minimum? If function evaluation is 170 and global minimum is -0.5, what does it mean? Is there a formula for function evaluation? How to calculate the numerical values of function evaluations in GA by using either command line or GUI?

Subject: Function evaluation in GA

From: Alan_Weiss

Date: 15 Jan, 2013 12:40:38

Message: 2 of 3

On 1/14/2013 11:44 PM, Dua wrote:
> What is function evaluation in GA? How to relate the values of
> function evaluations with global minimum? If function evaluation is
> 170 and global minimum is -0.5, what does it mean? Is there a formula
> for function evaluation? How to calculate the numerical values of
> function evaluations in GA by using either command line or GUI?

The basic documentation on fitness functions is here:
http://www.mathworks.com/help/gads/computing-objective-functions.html#bsdbxh4

There are many examples, including these:
http://www.mathworks.com/help/gads/example-rastrigins-function.html
http://www.mathworks.com/help/gads/genetic-algorithm-examples.html#f18421
http://www.mathworks.com/help/gads/genetic-algorithm-examples.html#f12085

Alan Weiss
MATLAB mathematical toolbox documentation

Subject: Function evaluation in GA

From: Steven_Lord

Date: 15 Jan, 2013 15:17:58

Message: 3 of 3



"Dua " <limsm@gmail.com> wrote in message
news:kd2mqr$83i$1@newscl01ah.mathworks.com...
> What is function evaluation in GA?

Whenever GA calls your objective function, that counts as one function
evaluation.

> How to relate the values of function evaluations with global minimum?

If you let GA evaluate your function enough times, it may (emphasis on MAY)
return the global minimum or may return a local minimum.

> If function evaluation is 170 and global minimum is -0.5, what does it
> mean?

After evaluating your objective function 170 times, GA found a minimum of
your function. The way you've phrased it is somewhat ambiguous; -0.5 may be
the minimum value of your objective function or it may be the coordinate at
which your objective function achieves its minimum value.

> Is there a formula for function evaluation?

Not really, unless you consider GA incrementing a counter whenever it calls
the objective function a formula.

> How to calculate the numerical values of function evaluations in GA by
> using either command line or GUI?

GA should return or display that information as one of its outputs or in one
of the fields of the GUI respectively.

--
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com

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