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I'm using matlab/octave and would like some help trying to improve the speed of my code. I've tried to vectorize the code but I run out of memory so I went back to for loops. What I'm trying to do is have a function that will allow me to shift an array cell by cell. The reason I'm doing this is to have exact precision over a signal. Once I shift the array I plan on adding several of them together and comparing them to the original signal.

I created a function along with some test code to test the speed. See times and code below

ii = 0 -elapsed time -67.5671sec- or -1.1261mins- or -0.0188hours-

ii = 14700 -elapsed time -613.3785sec- or -10.2230mins- or -0.1704hours-

ii = 29400 -elapsed time -1150.6487sec- or -19.1775mins- or -0.3196hours-

The code takes a long time to run on 1 second of an audio signal at a sample rate of 44100 any idea how I can speed this up and accomplish my goals?


function [array_shifted]=rtphaseshiftarraypts(sigarray,pts_to_shift)


cycle_permute_lt = @(sigarray, k) [sigarray(mod((1:end)-k-1, end)+1 )];

for ii=0:1:fs
    a_L=cycle_permute_lt(sigarray, ii+pts_to_shift);    

Test Code:

clear all, clc,clf,tic
y=fliplr(y); %just flipping y to look like milo wolffs

lr_sig=[y*1 -y*1];
for ii=0:round(fs/3):fs %ii=0:1:90 going right , ii=0:-1:-90 going left

    array_shifted_L=y*1; %ampcomb(ii);
    array_shifted_R=-y*1; %ampcomb(ii);
    fprintf('\n-elapsed time -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);


    axis([0 fs+100 -2 2])

    axis([0 fs+100 -2 2])

    axis([0 (fs*2)+100 -2 2])

    axis([0 (fs*2)+100 -2 2])
    str_title='Angle is '; 
    title([str_title,num2str(ii),' pts']) %turns of latex interperter so I can use underscores my way

    %hold on    
fprintf('\nfinally Done-elapsed time -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);
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closed as off topic by Dilip Sarwate, jonsca, Peter K., Lorem Ipsum Feb 13 '13 at 15:52

Questions on Signal Processing Stack Exchange are expected to relate to signal processing within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here.If this question can be reworded to fit the rules in the help center, please edit the question.

You seem to be incredibly confused about what you are trying to achieve... at least your matlab code incredibly confused me. Can you give a numeric (concrete) example using a size 10 array that shows what rtphaseshiftarraypts is trying to achieve? – Peter K. Feb 12 '13 at 20:23
@Peter K Sure if I have an array with 10 values 1,2,3,4,5,6,7,8,9,10 and I shift the array over three I would get 4,5,6,7,8,9,10,1,2,3 basically it's doing a permutation – Rick T Feb 12 '13 at 20:25
This is a programming question, not a signal processing question, and I vote to close. – Dilip Sarwate Feb 12 '13 at 20:44
@DilipSarwate: Agreed... though I've only just gained the voting rights! :-) – Peter K. Feb 13 '13 at 13:38
up vote 1 down vote accepted

Your example is to take:


and get:


I would just follow this example and use circshift, or that more detailed solution for multi-dimensional arrays.

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