MATLAB: Parfor with sliced and reduction variable

parfor

Hello, i'm trying to use parfor in this way:
oldc       = c(:,index);
delta      = thirds(biggy+1);
newc_left  = oldc(:,ones(1,lssize));
newc_right = oldc(:,ones(1,lssize));
f_left     = zeros(1,lssize);
f_right    = zeros(1,lssize);
 parfor i = 1:lssize
    lsi               = ls(i);
    newc_left(lsi,i)  = newc_left(lsi,i) - delta;
    newc_right(lsi,i) = newc_right(lsi,i) + delta;
    [f_left(i), con_left(i), fflag_left(i)]    = CallObjFcn(Problem,newc_left(:,i),a,b,impcons,calltype,varargin{:});
    [f_right(i), con_right(i), fflag_right(i)] = CallObjFcn(Problem,newc_right(:,i),a,b,impcons,calltype,varargin{:});
    fcncounter = fcncounter + 2;
end
There is something wrong with the use of newc-left. can I use parfor in this case and how?

Best Answer

You could try something like this so that you're updating whole columns of newc_left and newc_right:
numRows = size(oldc, 1);
...
parfor ...
  increment = zeros(numRows, 1);
  increment(lsi(i)) = delta;
  newc_left(:,i) = newc_left(:,i) - increment;
  newc_right(:,i) = newc_right(:,i) + increment;
  ...
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