plz explain error IN PSO CODE

Undefined operator '<' for input arguments of type 'struct'.

Error in TrainAnfisUsingPSO>RunPSO (line 103)
        if particle(i).Best.Cost<BestSol.Cost

CODE IS HERE:

 empty_particle.Position=[];
    empty_particle.Cost=[];
    empty_particle.Velocity=[];
    empty_particle.Best.Position=[];
    empty_particle.Best.Cost=[];

    particle=repmat(empty_particle,nPop,1);

    BestSol.Cost=inf;

    for i=1:nPop

        % Initialize Position
        if i>1
            particle(i).Position=unifrnd(VarMin,VarMax,VarSize);
        else
            particle(i).Position=ones(VarSize);
        end

        % Initialize Velocity
        particle(i).Velocity=zeros(VarSize);

        % Evaluation
        particle(i).Cost=CostFunction(particle(i).Position);

        % Update Personal Best
        particle(i).Best.Position=particle(i).Position;
        particle(i).Best.Cost=particle(i).Cost;

        % Update Global Best
        var1=particle(i).Best.Cost;
        var2=BestSol.Cost;

        if particle(i).Best.Cost<BestSol.Cost  %this line

            BestSol=particle(i).Best;

        end

    end

[Walter Roberson]

CostFunction is returning a struct rather than a numeric value. We would need to see the code to figure out why.

[jasleen kaur]

Problem.CostFunction=@(x) TrainFISCost(x,fis,data);

CostFunction calls the following function:

function out=TrainFISCost(x,fis,data)

      MinAbs=1e-5;
      if any(abs(x)<MinAbs)
          S=(abs(x)<MinAbs);
          x(S)=MinAbs.*sign(x(S));
      end

      p0=GetFISParams(fis);

      p=x.*p0;

      fis=SetFISParams(fis,p);

      x=[24,31,1,7,80,3,1,11.4285714300000,4,1.75000000000000;
          40,143,3,7,80,3,1,11.4285714300000,4,1.75000000000000;
          3194,1469,0,15,121,4,2,8.06666666700000,6,2.50000000000000;
          355,444,1,11,79,1,1,7.18181818200000,2,5.50000000000000;
          4622,1102,0,10,89,2,1,8.90000000000000,3,3.33333333300000;
          2062,1531,0,11,92,3,1,8.36363636400000,4,2.75000000000000;
          10,19,1,18,120,1,2,6.66666666700000,3,6;
          6724,2645,0,13,104,3,1,8,4,3.25000000000000;
          316,159,0,8,91,5,1,11.3750000000000,6,1.33333333300000;
          1177,372,0,15,114,3,1,7.60000000000000,4,3.75000000000000;
          48,95,1,7,80,3,1,11.4285714300000,4,1.75000000000000;
          90,570,6,8,58,0,1,7.25000000000000,1,8;
          5,5000,0,5,60,1,1,12,2,2.50000000000000;
          58,5,0,5,84,1,2,16.8000000000000,3,1.66666666700000;
          58,5,0,5,83,1,2,16.6000000000000,3,1.66666666700000;
          117,263,2,7,80,3,1,11.4285714300000,4,1.75000000000000;
          97,127,1,16,120,4,0,7.50000000000000,4,4;
          43,459,10,13,91,1,1,7,2,6.50000000000000;
          36374,3210,0,11,88,3,1,8,4,2.75000000000000;
          3091,979,0,13,90,2,1,6.92307692300000,3,4.33333333300000]  ;  

      t=[
      1,1,0,0,0,0,0,0,1,0,1,0,1,1,0,1,0,0,0,0;    
      ];

      y=evalfis(x,fis,100);

      e=t-y;

      %MSE=mean(e(:).^2);
      %RMSE=sqrt(MSE);

      %z=RMSE;

    out.fis=fis;
    % out.y=y;
    %out.e=e;
      %out.MSE=MSE;
      %out.RMSE=RMSE;

end

[jasleen kaur]

Ok I got the error!! Thank you sir for pointing it out!! :)