MATLAB: Parfor Step

Question

I am attempting to run a ParFor statement with a step function and Matlab is giving me an error "The range of a parfor statement must be increasing consecutive integers. See Parallel Computing Toolbox, "parfor"." I'm wondering if this is possible or if I have to do some manipulation to my loop to get this to work in parallel. Would someone be able to make a suggestion as to how to modify one of these loops so that it will work in parallel?

Simplified Example

      parfor (i = 1:10:75,8)
          test3(i)= i*3;
      end

Real Example

parfor (i = 1:10:75,8)
    tic
    recnum = min(i+9,length(test));
    datainsert(conn,'dbo.tbl_FactorExposure_Security',{'CUSIP','MktDate','Factor_Exp','Factor_Num'},MyData(i:recnum,:));
    disp(i)
    toc
end

Thanks a lot! Brian

Answer 1

As the doc states, PARFOR needs to work with unit-step ranges. So you do need to re-work the loop slightly, something like this:

   idx = 1:10:75;
   parfor (i = 1:numel(idx), 8)
     val = idx(i);
     test3t(i) = val * 3;
   end

That example leaves 'test3t' slightly different to 'test3' in your example, you can rearrange things by doing

test3(idx) = test3t;