speed up the code

Question

Tiki Tiki 2018-7-23

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/411607-speed-up-the-code

评论： Jan 2018-8-3

采纳的回答： Jan

在 MATLAB Online 中打开

hi everyone.

can you help me speed up this code?

    tic
    InputOverlap = magic(64)
    SDR_Overlap = InputOverlap;
    SDR = (zeros (64,64)) ;
    Radius = 2;
    InputOverlap = [InputOverlap(:,1:Radius) InputOverlap InputOverlap(:,end+1-Radius:end)];
    InputOverlap = [InputOverlap(1:Radius,:) ; InputOverlap ; InputOverlap(end+1-Radius:end,:) ];
        for r=1:64
        for c=1:64
            Neighbour= InputOverlap(r:r+2*Radius,c:c+2*Radius);
            Kmax = max(Neighbour(:)) ;
            if (SDR_Overlap(r,c)>0)&(SDR_Overlap(r,c)>=  Kmax) 
              SDR(r,c) = 1;
            else
              SDR(r,c) = 0;
            end
        end
        end
        toc

Thanks.

2 个评论
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Jan 2018-7-23

编辑：Jan 2018-7-23

在 MATLAB Online 中打开

Start with omitting:

 else
   SDR(r,c) = 0;

SDR is initialized to zero already.

The editor should show a hint that && is more efficient than &. Consider these MLint messages.

The main part of your code happens before the loop. Most of all displaying the magic matrix is slow. I guess, you want to measure the time inside the loop only, don't you?

Tiki Tiki 2018-7-26

Yes. My problem is time in the loop. I remove SDR(r,c) = 0 by setting it is zeros before loop.

But time consumes still high. How can I remove loop in this case?

Please help me. Thank.

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Answer 1

Jan 2018-7-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/411607-speed-up-the-code#answer_329943

在 MATLAB Online 中打开

This is slightly faster:

tic
for r = 1:64
  for c = 1:64
      Neighbour = InputOverlap(r:r+2*Radius, c:c+2*Radius);
      Kmax      = max(Neighbour(:));
      SDR(r,c)  = (SDR_Overlap(r,c) >= Kmax);
  end
end
toc