how to increase the number of workers to 32 for parfor loop

I am trying to increase the number of workers (cores) for parfor loop in Matalb, but after running the code the number of cores was limited to 12

   parfor (i=1:size(data,2),32)
    filename=[surfacename,num2str(sub),var,num2str(file_no(i)),'.raw'];
    fullname=fullfile(Dir,filename);
    fid = fopen(fullname,'rb'); % rb = read binary
    NN=N*10;
    data2 = fread(fid,NN,'single');
    fclose(fid);
    start=8;
    data2=data2(start:length(data2));
    len=length(data2)/no_variables;
    if opt==1 ||opt==6;
    data(:,i)=data2(1:len);
    elseif opt==2;
    data(:,i)=data2(len+1:2*len);
    elseif opt==3;
    data(:,i)=data2(2*len+1:3*len);
    elseif opt==4;
    data(:,i)=data2(3*len+1:4*len);
    elseif opt==5;
    data(:,i)=data2(4*len+1:5*len);
    elseif opt==7;
    F = scatteredInterpolant(x,y,z,data2(1:len),'linear','linear');
    data_int=F(xq,yq,zq);
    data_int_2= reshape(data_int,[],1);
    data(:,i)=data_int_2;
    elseif opt==8;
    F = scatteredInterpolant(x,y,z,data2(len+1:2*len),'linear','linear');
    data_int=F(xq,yq,zq);
    data_int_2= reshape(data_int,[],1);
    data(:,i)=data_int_2;
    elseif opt==9;
    F = scatteredInterpolant(x,y,z,data2(2*len+1:3*len),'linear','linear');
    data_int=F(xq,yq,zq);
    data_int_2= reshape(data_int,[],1);
    data(:,i)=data_int_2;
    elseif opt==10;
    F = scatteredInterpolant(x,y,z,data2(3*len+1:4*len),'linear','linear');
    data_int=F(xq,yq,zq);
    data_int_2= reshape(data_int,[],1);
    data(:,i)=data_int_2;
    elseif opt==11;
    F = scatteredInterpolant(x,y,z,data2(4*len+1:5*len),'linear','linear');
    data_int=F(xq,yq,zq);
    data_int_2= reshape(data_int,[],1);
    data(:,i)=data_int_2;
    end
      if mod(i,500) == 0
      fprintf('flie read %d...\n',i);
      tt=toc/60
      end
      name=[name,i];
end
    

The output showed that the number of workers are only 12.Is there any method to increase them?

Answer 1

[Raymond Norris]

Are you explicitly calling parpool?

parpool(32);

Alternatively, you can change the default by going to the Parallel preferences and changing Preferred number of workers in a parallel pool