using genetic algorithm for optimization

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i have this error message
??? Subscripted assignment dimension mismatch.
Error in ==> fcnvectorizer at 14
y(i,:) = feval(fun,(pop(i,:)));
Error in ==> makeState at 47
Score =
fcnvectorizer(state.Population(initScoreProvided+1:end,:),FitnessFcn,1,options.SerialUserFcn);
Error in ==> gaunc at 41
state = makeState(GenomeLength,FitnessFcn,Iterate,output.problemtype,options);
Error in ==> ga at 279
[x,fval,exitFlag,output,population,scores] = gaunc(FitnessFcn,nvars, ...
Error in ==> main at 11
[x,fval,exitflag,output,final_pop]=ga(FitnessFcn,nvar,options);
Caused by:
Failure in user-supplied fitness function evaluation. GA cannot continue.

Accepted Answer

Alan Weiss
Alan Weiss on 29 Mar 2013
Apparently there is an error in your fitness function. If it isn't too long, please post it so we can see what might be the problem.
And please include your gaoptimset calls and your function call to ga (e.g., x = ga(@main,4,A,b) )
Alan Weiss
MATLAB mathematical toolbox documentation

More Answers (3)

Walter Roberson
Walter Roberson on 29 Mar 2013
Your fitness function is returning your input values x_pop as its first return value. It should not be doing that. The documentation indicates,
fitnessfcn
Handle to the fitness function. The fitness function should accept a row vector of length nvars and return a scalar value.
When the 'Vectorized' option is 'on', fitnessfcn should accept a pop-by-nvars matrix, where pop is the current population size. In this case fitnessfcn should return a vector the same length as pop containing the fitness function values. fitnessfcn should not assume any particular size for pop, since ga can pass a single member of a population even in a vectorized calculation.
So your fitnessfcn should only be returning a single variable, not two variables, and (unless you have Vectorized turned on) return a scalar such as fx_val .
  1 Comment
mado
mado on 29 Mar 2013
do you mean that i should write it function [ fx_val]=PID_objfun_ITAE(x_pop,options)

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mado
mado on 29 Mar 2013
Edited: Walter Roberson on 29 Mar 2013
this is the fitness function code
function [x_pop, fx_val]=PID_objfun_ITAE(x_pop,options)
KP=x_pop(1);
KI=x_pop(2);
simopt = simset('solver','ode45','SrcWorkspace','Current','DstWorkspace','Current'); % Initialize sim options
[tout,xout,yout] = sim('pid_INC_GA',[0 .1],simopt);
t =0:0.1:30;
for i=1:301
error(i) = (abs(26.3-yout(i)))*t(i);
error=error*error';
ISE=sum(error);
end
sys_overshoot=max(yout)-26.3; % compute the overshoot
alpha=10;beta=1;
fx_val=ISE*beta+sys_overshoot*alpha;
  9 Comments
mado
mado on 29 Mar 2013
size of them all are [1 1] and i typed dbcont it gives the error message directly

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mado
mado on 30 Mar 2013
i make the function return one variable fx-val but the program is iterating as it is in a loop and restart its work without stopping i don't think its the for loop of error cause i removed it and it gives error message this is a part of it "??? Error using ==> PID_objfun_ITAE at 28 Error due to multiple causes.
Error in ==> validate>@(x)fitness(x,FitnessFcnArgs{:}) at 136 fitness = @(x) fitness(x,FitnessFcnArgs{:});

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