Alternate method for bin2dec function
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Gayathri Vijay
el 28 de Abr. de 2017
i m looking for an alternate method for bin2dec conversion to speed up my code. bin2dec functions takes 2.5 to 3 sec as run time.Is there any solution. Here is my code:
tic
img = randi([0, 255], 256, 256);
y=dec2bin(img(:),8);
I=reshape(y,256,2048);
P1=reshape(bin2dec(num2str(reshape(I, 65536, []))), 256, 256);
toc
Elapsed time is 1.494633 seconds.
selftime of bin2dec-----1.420 s
Thanks in advance
3 comentarios
Walter Roberson
el 28 de Abr. de 2017
The output of dec2bin is a character array. You reshape that a couple of times (why not just once?), and then you num2str() what is already string, which is a step that will leave things unchanged. Then you bin2dec() that.
Are we to understand from this that there is a hidden transmission over serial line and reception with fscanf('%d') between the creation of y and P1 ?
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Jan
el 28 de Abr. de 2017
Editada: Jan
el 30 de Abr. de 2017
You can create a lean version of dec2bin:
function x = myBin2Dec(s)
% Lean version of Matlab's BIN2DEC, see: help bin2dec
n = size(s, 2);
v = s - '0';
twos = pow2(n-1:-1:0);
x = v * twos.';
This reduces the runtime from 0.102 to 0.048 seconds and dec2bin is the bottleneck - you know how to create a lean version now.
I cannot imagine how you get 1.5 seconds. My machine is an old 2.3GHz Core2Duo. Perhaps you have a clear all before and the time is required to reload the files from the disk?
Similar to Steven's question: What is the purpose of the code? I assume that there is a faster version without the conversion to the binary strings.
6 comentarios
Jan
el 30 de Abr. de 2017
@Gayathri Vijay: My code is a lean version of the original bin2dec, so it expectes exactly the same inputs.
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