Problem with parfor loop (not enough input arguments)

Question

Swapnil Sayan Saha 2019-5-25

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/463995-problem-with-parfor-loop-not-enough-input-arguments

评论： Swapnil Sayan Saha 2019-6-5

I'm having problem with the following snippet of code:

parfor i = 1:196072
	z = x(i,:);
	z1 = filter(Hd, z);
	fprintf(fid, '%20.6f', z1);
	fprintf(fid, '\n');
end
fclose(fid);  

As soon as I run the code snippet, it says: Not Enough Input Arguments.

However, the code works fine using normal for loop. I tried shutting down and restarting Parpool but no effect. I also tried restarting MATLAB, no effect. I tried deleting local_cluster_jobs folder in C:/Users/AppData/Roaming/MATLAB but no effect.

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Walter Roberson 2019-5-26

Is Hd possibly a global variable?

Swapnil Sayan Saha 2019-5-26

在 MATLAB Online 中打开

I solved it.

The filter function can work in two ways:

First method: filter function works with a filter object: filter(Hd, x), where Hd is a filter object exported from FilterDesigner... second method: filter function works with filter coefficients: filter(b,a,x), where b and a are filter transfer function coefficients.. x is the signal..

For some reason, parfor loop cannot process Hd.. So i just exported the coefficents in the workspace and used them inside the loop, also made a couple of changes to better optimize memory usage.

fid = fopen('bagaccx_f.txt','w');
fclose(fid);
parfor i = 1:196072
   fid = fopen('bagaccx_f.txt','a');
   fprintf(fid, '%f\t', filter(b,a, x(i,:)));
   fprintf(fid, '\n');
   fclose(fid);
end

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Answer 1