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iterlin and iterget

version 1.2.0.0 (2.1 KB) by Samuel Bandara
Linearize nested loops for smarter dispatch by parfor

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Updated 17 Dec 2013

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MATLAB does not allow nested parfor loops, resulting in idle time for workers at loop boundaries. In the following example, no loop is a good choice for conversion to parfor:

for plate = 1 : 3
for row = 2 : 7
for col = 4 : 9
% time-consuming computations here %
end
end
end

A solution for having workloads from within nested loops be dispatched to workers without idling is to linearize, but that approach becomes cumbersome if ranges do not start from one. Now, iterlin and iterget provide a simple pattern:

rng = [1, 3; 2, 7; 4, 9];
parfor k = iterlin(rng)
[plate, row, col] = iterget(rng, k);
% time-consuming computations here %
end

With the above pattern, you reduce idle time for workers, and no longer need to think about which loop to convert to parfor.

Cite As

Samuel Bandara (2020). iterlin and iterget (https://www.mathworks.com/matlabcentral/fileexchange/44561-iterlin-and-iterget), MATLAB Central File Exchange. Retrieved .

Comments and Ratings (1)

KAE

Some more background on using this function is here, https://stackoverflow.com/questions/20295579/how-to-nest-multiple-parfor-loops

Updates

1.2.0.0

Fix for earlier releases, going back at least to 2012b.

1.1.0.0

Added a specific usage example in the description.

MATLAB Release Compatibility
Created with R2012b
Compatible with any release
Platform Compatibility
Windows macOS Linux
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