How to execute parallel functions ?

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Paul-Henri Michel 2013-4-22

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Hi everyones,

I have a three buffer system and It takes 3 steps : - I need to collect data from a .txt file - I need to filter these data - I need to plot the filtered data

I want to do these three steps simultaneously ! (even if I have a delay between current data and plotted data) Should I use a parfor loop, matlabpool or multi-thread programming ?

Thanks a lot !

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Paul-Henri Michel 2013-4-22

Notice I need to have all the computed data on the same workspace, and I have to use these at each moment.

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Friedrich 2013-4-24

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编辑：Friedrich 2013-4-24

在 MATLAB Online 中打开

Hi,

look at createTask and createJob. You create a Task for each file, let the worker process is and pass the data back to MATLAB. In MATLAB you get that data and plot it and restart the process:

c = parcluster; %or maybe c = findResource('scheduler','Configuration','local');
job = createJob(c);
for i=1:3
    createTask(job,@rand,1,{i}); 
%create a function handle to the function you use to process the file, pass in the filename as argument to the function to be able to use the same function for all files
end
submit(job);
wait(job);
results = job.fetchOutputs %maybe you need getAllOutputArguments depends on the version you are using
job.delete

Or use SPMD (this should give a better peformance as CreateJob/CreateTask because te workers need to be started only once)

matlabpool open 3
result = cell(3,1);
spmd
   switch labindex
       case 1
           result{1} = rand(1); %process file 1
       case 2
           result{2} = rand(2); %process file 2
       case 3
           result{3} = rand(3); %process file 3
   end
end
%each worker holds its own result because result is a Composite object
result
result{:}

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Paul-Henri Michel 2013-4-23

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No answers ?

Thanks !

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Paul-Henri Michel 2013-4-23

编辑：Paul-Henri Michel 2013-4-23

No I mean one Matlab for computing and one Matlab for plotting. Once the first Matlab has finished to filter data, I send the data to the second Matlab, which display these on a "hold on" figure and I restart the operation !

But maybe the UDP protocol is too slow to do this, because my file data contain more than 4 000 characters.

Friedrich 2013-4-23

Plotting doesnt take much time. Using a MATLAB for Plotting only seems a bit too much. I would do all that in one MATLAB. You can use PCT to read in the 3files and post process it. You then use these results and plot it and then start over again. This can run in 1 MATLAB.

You use the second MATLAB for your own.

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Paul-Henri Michel 2013-4-23

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Ok, now I don't consider plotting data, I just want read data and filter data (other data obviously) simultaneously. In fact, I need two workers on the same workspace ?

Should I use parfor loop, matlabpool ?

Thanks !