extra paramters to ga output function

I want to write an output function to the ga algorithm that will use and also change variables in my workspace in each iteration (plots, changes to a connected device etc). I read about it in the documentation but I couldn't quite figure it out. I would like to avoid using global variables, so is there a syntax example on how to add these extra input and output parameters? For example (which I know is incorrect but explains my intentions):

function [state,options,optchanged,a,b] = gaIterationOutput(options,state,flag,a,b,c,d)

% Do stuff with state,options,optchanged
% Do stuff with a,b,c,d

end

Here a,b,c,d are extra input parameters, and a,b are also sent as output parameters to the workspace. I understand it somehow needs to be done using anonymous functions, but I didn't understand exactly how.

Also, is it necessary to explicitly write

optchanged = false;

as can be seen in examples? (That is indeed the case with my code)

Thanks.

Answer 1

[Johnathan Viernik]

Ok, I've managed to solve all my porblems. I still don't know how to use the suggested nested function, but instead I used handles to send extra parameters to the function, as in my above comment to Walter Roberson. In order to change variables in the base workspace I used the commands

evalin
assignin

So now I have full control over any variable through the ga's output function.

A nice thread I found, if anyone wants to review these commands: Use of evalin and assignin in ga output function

Answer 2

[Walter Roberson]

Yes, it is necessary to optchanged = false;

It is not possible to have extra outputs.

In your situation I would suggest not having the extra variables as inputs or outputs. Instead I would suggest that you use nested functions with shared variables. See http://www.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html#f0-50984

[Johnathan Viernik]

Thanks for your reply. I still don't understand how to use them though. Where am I supposed to define the nested function? It can't be defined inside the outputfunc since its scope doesn't contain the needed variables; it can't be defined inside main; so my only idea is to define it inside the ga script or something, but it too doesn't have access to all of main's workspace. Thanks again.

[Johnathan Viernik]

Ok I partly figured this out. Instead of passing an output function

gaoutputfunc(options,state,flag)

I used handles to pass

@(options,state,flag)gaoutputfunc(options,state,flag,[extra parameters])

I can now work with these params inside the function. The only thing left is to be able to send information back to the main workspace.

[Walter Roberson]

Nest the definition of the output function within the function that defines the variables you want to be able to alter, which might be the main function.

[Kurt Stewart]

Use this to have it pass through the state

state.extra_param=extra_param 

Then you can save things in the output function

case {'iter','interrupt'}
        disp('Iterating ...')
        fname=[pwd,'\','analysis',date_var,'.mat'];
        gen_num=state.Generation;
        %gen_str=['gen',num2str(gen_num)]
        gen_data(gen_num).state=state;
        save(fname,'gen_data')

Hope this helps any in the future!

[Kurt Stewart]

I am not sure how you got your solution to work, but I am working on it