MATLAB: Gamultiobj output function error

gamultiobjMATLABoutput function

Hi,
I have a multiobjective opimization problem and want to solve it with gamultiobj. I want to save the optimized values of my objective functions after every iteration in an array. I found the example code for the output function here: http://de.mathworks.com/help/optim/ug/output-functions.html . But when I apply the example code to my problem, like this:
 function [history,searchdir] = runfmincon
 FitnessFunction = @needfunction;
 numberOfVariables = 8;
 lb = zeros(1,8);
 ub = [];
% Set up shared variables with OUTFUN
 history.x = [];
 history.fval = [];
 searchdir = [];
 options = gaoptimset('PlotFcns',@gaplotpareto,'UseParallel',true,'OutputFcns', @outfun,'PopulationSize',5);
 xsol = gamultiobj(FitnessFunction,numberOfVariables,[],[],[],[],lb,[],options);
 function stop = outfun(x,optimValues,state)
     stop = false;
     switch state
         case 'init'
             hold on
         case 'iter'
         % Concatenate current point and objective function
         % value with history. x must be a row vector.
           history.fval = [history.fval; optimValues.fval];
           history.x = [history.x; x];
         % Concatenate current search direction with 
         % searchdir.
           searchdir = [searchdir;... 
                        optimValues.searchdirection'];
           plot(x(1),x(2),'o');
         % Label points with iteration number and add title.
         % Add .15 to x(1) to separate label from plotted 'o'
           text(x(1)+.15,x(2),... 
                num2str(optimValues.iteration));
           title('Sequence of Points Computed by fmincon');
         case 'done'
             hold off
         otherwise
     end
 end
 end
I get the following error:
 Error using runfmincon/outfun
 Too many output arguments.
 Error in gaoutput (line 39)
    [state,optnew,changed] = feval(functions{i},options.OutputPlotFcnOptions,state,flag,args{i}{:});
 Error in gamultiobjsolve (line 13)
 [state,options] = gaoutput(FitnessFcn,options,state,currentState);
 Error in gamultiobj (line 274)
 [x,fval,exitFlag,output,population,scores] = gamultiobjsolve(FitnessFcn,nvars, ...
 Error in runfmincon (line 16)
 xsol = gamultiobj(FitnessFunction,numberOfVariables,[],[],[],[],lb,[],options);
It would be great, if someone could help me out

Best Answer

The genetic algorithm has a different syntax for output functions than Optimization Toolbox functions. The syntax is described here. After you correct your syntax things will most likely work (I didn't check in detail, but everything else looks reasonable).
Alan Weiss
MATLAB mathematical toolbox documentation
Related Question