Helo everyone, I want to ask about my error in matlab. Error: File: Untitled5.m Line: 57 Column: 56 -> (rand(1,nv​ar).*c1.*(​pbest(pop,​:)x(pop,:)​)+...) Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or

maxpop=100; % maximum population
maxiter=1000; % maximum iteration
numtry=10; % number of trial runs
bestAll=zeros(numtry,2);
bestxAll=zeros(numtry,4); %two variable x y 

function [record,gbestfit,gbest]=PSO(maxpop,maxiter)
 
% initial parameter
ub=[2 3]; % upper-bound variables
lb=[0 0]; % lower-bound variables
w=0.5;c1=2;c2=2; % pso parameters
vmax=(ub-lb)*0.8; % damping limit 80% of search space
pc=0.1; % crazy particle probability
 
nvar=length(ub); % number of variables
 
%initialize the population
x=zeros(maxpop,nvar);
fit=zeros(maxpop,1);
for i=1:maxpop
   x(i,:)=rand(1,nvar).*(ub-lb)+lb; %randomize between ub and lb
   fit(i,:)=objfunc(x(i,:),1); % evaluate fitness function
end
 
v=rand(maxpop,nvar).*ones(maxpop,nvar)*2-ones(maxpop,nvar); % randomize first velocity between -1 and 1
pbest=x; % has no history so the best is the first one
pbestfit=fit; % has no history so the best is the first one
[gbestfit,index]=max(pbestfit); % find gbest by comparing pbest
gbest=pbest(index,:);
 
record=zeros(maxiter,1);
for iter=1:maxiter
    for pop=1:maxpop
        % update velocity
        v(pop,:)=w*v(pop,:)+...
 			rand(1,nvar).*c1.*(pbest(pop,:)x(pop,:))+...
 			rand(1,nvar).*c2.*(gbest-x(pop,:));
        
% velocity damping
indexover=find(abs(v(pop,:))>vmax); % find the velocity that exceed vmax  
v(pop,indexover)=v(pop,indexover)./abs(v(pop,indexover)).*vmax(1,indexover); %damp that velocity
        
        % update location
        if rand() > pc % normal
            x(pop,:)=x(pop,:)+v(pop,:);
        else % crazy particle
            x(pop,:)=x(pop,:)+rand()*v(pop,:)./abs(v(pop,:)).*vmax; % crazy particle velocity can be + or -
        end
        
        % fix out of boundary particles
        indexlb=find(x(pop,:)<lb); % find index that is less than lower bound
        indexub=find(x(pop,:)>ub); % find index that is more than upper bound
        x(pop,indexlb)=lb(1,indexlb)+abs(x(pop,indexlb)-lb(1,indexlb)); % the particle bounces off the lower boundary
        x(pop,indexub)=ub(1,indexub)-abs(x(pop,indexub)-ub(1,indexub)); % the particle bounces off the upper boundary
       
        % calculate fitness
        fit(pop,1)=objfunc(x(pop,:),iter); % evaluate fitness function
        
        % find pbest
        if fit(pop,1)>pbestfit(pop,1) % update pbest if fitness is better
            pbestfit(pop,1)=fit(pop,1);
            pbest(pop,:)=x(pop,:);
        end
        
        % find gbest
        if fit(pop,1)>gbestfit % update gbest if fitness is better
            gbestfit=fit(pop,1);
            gbest=x(pop,:);
        end
    end
    record(iter,1)=gbestfit; % record for plotting convergence history
end
end

Helo everyone, I want to ask about my error in matlab.

Error: File: Untitled5.m Line: 57 Column: 56 -> (rand(1,nvar).*c1.*(pbest(pop,:)x(pop,:))+...)

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error.

To construct matrices, use brackets instead of parentheses.

How I can solve thats problem? thank you

Answer 1

[Stephan]

Line 36:

for iter=1:maxiter
    for pop=1:maxpop
        % update velocity
        v(pop,:)=w*v(pop,:)+...
 			rand(1,nvar).*c1.*(pbest(pop,:)x(pop,:))+...
            %                                          ^
            %                                          |
            %                                          ---> Missing '*' or '+' or...
            %
 			rand(1,nvar).*c2.*(gbest-x(pop,:));