parfor

Can a Matlab PARFOR loop be programmatically switched on/off?

由 江枫思渺然 提交于 2019-12-10 12:56:30
问题 Have a simple question about parfor in MATLAB. I would like to set a flag in my program to change between parfor and regular for loops. Basically, I need this functionality so that some parts of my code can update graphics in a "debug" mode, then when the flag is turned off, use parfor with no graphics updates for speed. So, I'm looking for something simple that has this functionality: if (flag) for i = 1:n else parfor i = 1:n end % Do loop tasks. end Any help would be greatly appreciated!

Difference between distributed and non-distributed arrays in MATLAB

由 江枫思渺然 提交于 2019-12-09 23:47:40
问题 Suppose that we have this code in MATLAB: parpool('local',2) % Create a parallel pool W = ones(6,6); W = distributed(W); % Distribute to the workers spmd T = W*2; % Calculation performed on workers, in parallel % T and W are both codistributed arrays here end T % View results in client. whos % T and W are both distributed arrays here delete(gcp) % Stop pool I read in documentation that the difference between normal arrays and distributes array is : When we use distributed arrays, these arrays

How does MATLAB's parfeval function work?

由 末鹿安然 提交于 2019-12-09 06:46:28
问题 In the MATLAB documentation we have a code example for the parfeval function. I have some questions about it. This is the code: p = gcp(); %// To request multiple evaluations, use a loop. for idx = 1:10 f(idx) = parfeval(p,@magic,1,idx); % Square size determined by idx end %// Collect the results as they become available. magicResults = cell(1,10); for idx = 1:10 %// fetchNext blocks until next results are available. [completedIdx,value] = fetchNext(f); magicResults{completedIdx} = value;

Handle classes with Matlab parfor loops [closed]

由 我是研究僧i 提交于 2019-12-08 13:41:47
问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 3 years ago . I consult "Handle Classes" section of http://uk.mathworks.com/help/distcomp/objects-and-handles-in-parfor-loops.html and write this: parfor j = 1:length(stores) store = stores(j); dataj = somefunction(store.someproperty, data(data.store == store.id, :)); stores(j) = store.dosomething(dataj); end where

Vector values differ if accessed outside or from within parfor

由 我与影子孤独终老i 提交于 2019-12-07 06:22:40
问题 I have created this test Matlab script file: numbers = [29 37 44 54 62]; for i=1:length(numbers) fprintf('%d\n', numbers(i)); end fprintf('***\n'); matlabpool local 5; parfor i=1:length(numbers) fprintf('%d\n', numbers(i)); end % image loop fprintf('***\n') for i=1:length(numbers) fprintf('%d\n', numbers(i)); end matlabpool close; fprintf('***\n'); for i=1:length(numbers) fprintf('%d\n', numbers(i)); end When I run it, I get consistently the following output: 29 37 44 54 62 *** 112 111 107

When does Matlab choose to thread when using codegen and parfor

由 末鹿安然 提交于 2019-12-06 12:14:54
问题 I seem to be one of few people using the Matlab coder (codegen command) to get speedup, judging by the fact that there is so little discussion or help on-line. I've gotten incredible speedups from it in some cases. I've never seen it documented, but when I make a MEX file using codegen from a Matlab script with a parfor loop, it often will thread the resulting MEX. Parfor in functions spawns multiple processes which is often less efficient than just threading (I'm inferring all this from

Simulink-Simulation with parfor (Parallel Computing)

由 ＊爱你＆永不变心＊ 提交于 2019-12-05 20:17:05
I asked today a question about Parallel Computing with Matlab-Simulink. Since my earlier question is a bit messy and there are a lot of things in the code which doesnt really belong to the problem. My problem is I want to simulate something in a parfor-Loop, while my Simulink-Simulation uses the "From Workspace" block to integrate the needed Data from the workspace into the simulation. For some reason it doesnt work. My code looks as follows: load DemoData path = pwd; apool = gcp('nocreate'); if isempty(apool) apool = parpool('local'); end parfor k = 1 : 2 load_system(strcat(path,'\DemoMDL'))

How to set the max number of workers in parpool/matlabpool from console?

由 我的未来我决定 提交于 2019-12-05 17:03:38
问题 I know how to change the maximum number of workers using the Parallel preferences window in Matlab, but I cannot find any documentation about how to make changes on the preferences from console/code, and specifically about how to change the maximum number of workers I can use in a forloop. Any help will be greatly appreciated. 回答1: You want the parpool function. With no arguments it creates a default number of workers, with an integer argument it creates that many workers. If you just use a

Vector values differ if accessed outside or from within parfor

由 狂风中的少年 提交于 2019-12-05 10:26:49
I have created this test Matlab script file: numbers = [29 37 44 54 62]; for i=1:length(numbers) fprintf('%d\n', numbers(i)); end fprintf('***\n'); matlabpool local 5; parfor i=1:length(numbers) fprintf('%d\n', numbers(i)); end % image loop fprintf('***\n') for i=1:length(numbers) fprintf('%d\n', numbers(i)); end matlabpool close; fprintf('***\n'); for i=1:length(numbers) fprintf('%d\n', numbers(i)); end When I run it, I get consistently the following output: 29 37 44 54 62 *** 112 111 107 117 115 *** 29 37 44 54 62 *** 29 37 44 54 62 The fprintf within the parfor block prints the seemingly

Difference between distributed and non-distributed arrays in MATLAB

由 蹲街弑〆低调 提交于 2019-12-04 20:23:27
Suppose that we have this code in MATLAB: parpool('local',2) % Create a parallel pool W = ones(6,6); W = distributed(W); % Distribute to the workers spmd T = W*2; % Calculation performed on workers, in parallel % T and W are both codistributed arrays here end T % View results in client. whos % T and W are both distributed arrays here delete(gcp) % Stop pool I read in documentation that the difference between normal arrays and distributes array is : When we use distributed arrays, these arrays directly send to workers and there isn't any array on clients. So we don't have any access to these
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