by Forrest Sheng Bao http://fsbao.net

Well, a line of code is more meaningful than a thousand sentences. Here is the beef!

The MATLAB code:

%%%%%%%%%%%%%% begin test 1 %%%%%%%%%%%%%%%%%% clear all; clc scale = 8192*8192; A=zeros(1,scale); for i=1:scale A(i) = sin(i*2*pi/1024); end serial_time = toc tic parfor i=1:scale A(i) = sin(i*2*pi/1024); end parallel_time = toc %%%%%%%%%%%%%% END of test 1 %%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%% BEGIN of test 2 %%%%%%%%%%%%%%% clear all; scale2 = 10; a= zeros(scale2); tic for k = 1:scale2 a(k) = max(eig(rand(300))); end serial_time2 = toc matlabpool open local 2 tic parfor k = 1:scale2 a(k) = max(eig(rand(300))); end parallel_time2 = toc matlabpool close %%%%%%%%%%%%%% END of test 2 %%%%%%%%%%%%%%%

The timing result:

serial_time = 0.0048 parallel_time = 0.2451 serial_time2 = 3.8324 Starting matlabpool using the 'local' configuration ... connected to 2 labs. parallel_time2 = 2.5019 Sending a stop signal to all the labs ... stopped.

Therefore, using

`parfor`

does not guarantee speed up all the time.
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