How to avoid double for-loop

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Lucius
Lucius 2015-4-21
评论： Star Strider 2015-4-21
I have the following code
for n = 1:N
for l = 1:N
phase = exp(1i * (rand*0.5*pi-0.25*pi));
Efield_x(n,l) = Efield_x(n,l) .* phase;
end
end
with N=2^10 . Each matrix element should be multiplied with a different random number from -0.25*pi to 0.25*pi . Although the computer is running ("busy") I am waiting for 15 minutes now. How can we avoid this slow double for-loop to fasten to process significantly? By the way, I have 8 GB Ram.

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Star Strider
Star Strider 2015-4-21
This seems to work:
N = 2^10;
Efield_x = ones(N); % Create Data
phase = exp(1i * (rand(N)-0.5)*0.25*pi);
Efield_x = Efield_x .* phase;
  2 个评论
Lucius
Lucius 2015-4-21
编辑：Lucius 2015-4-21
you mean
...(rand(N)-0.5)*0.5*pi);
This works, thanks.
Star Strider
Star Strider 2015-4-21
My pleasure.
You’re correct on ‘phase’, with 0.5 rather than 0.25 as the multiplier to produce ±0.25*pi.

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