Re: Incompatibility MATLAB-OCTAVE : xcorr.m
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Re: Incompatibility MATLAB-OCTAVE : xcorr.m
by Søren Hauberg
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ons, 21 10 2009 kl. 13:12 +0200, skrev Jaroslav Hajek:
> > When calling > > > > function [R, lags] = xcorr (X, Y, maxlag, scale) > > > > In octave, having maxlag longer than X returns an error message. > > In Matlab, that is perfectly OK and zeros are padded around of the > > correlation "center" when that is the case (and which is true > > mathematically-wise). I think the attached patch fixes this, but since you didn't provide an example I'm not sure. It would be nice if you could possibly test this. Thanks, Søren [xcorr.patch] Index: xcorr.m =================================================================== --- xcorr.m (revision 6347) +++ xcorr.m (working copy) @@ -127,8 +127,12 @@ if !isscalar(maxlag) && !isempty(maxlag) error("xcorr: maxlag must be a scalar"); endif - if maxlag>N-1, - error("xcorr: maxlag must be less than length(X)"); + if (maxlag > N-1) + pad_result = maxlag - (N - 1); + maxlag = N - 1; + %error("xcorr: maxlag must be less than length(X)"); + else + pad_result = 0; endif if isvector(X) && isvector(Y) && length(X) != length(Y) && \ !strcmp(scale,'none') @@ -204,8 +208,12 @@ R = R.'; endif + ## Pad result if necesary + R = [zeros(1, pad_result), R, zeros(1, pad_result)]; + ## return the lag indices if desired if nargout == 2 + maxlag += pad_result; lags = [-maxlag:maxlag]; endif ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Octave-dev mailing list Octave-dev@... https://lists.sourceforge.net/lists/listinfo/octave-dev |
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Re: Incompatibility MATLAB-OCTAVE : xcorr.m
by Jaroslav Hajek-2
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On Fri, Oct 23, 2009 at 9:39 AM, Søren Hauberg <soren@...> wrote:
> fre, 23 10 2009 kl. 10:43 +1100, skrev Pierre Lonchampt: >> Thanks a lot Soren, apologies for my incomplete reporting; >> Your patch works for my application indeed. >> >> an example being: >> >> octave:22> x=rand(1,60) >> octave:23> y=xcorr(x,70,'coeff') >> octave:24> size(y) >> ans = >> >> 1 141 >> >> which was giving previously an error...now giving a result similar to >> Matlab > > Okay, thanks. > >> Pushing it a bit further, I just found some other minor discrepancies: >> >> Octave 3.0.1 (with the xcorr+your patch) >> octave:14> xcorr(ones(1,2),ones(1,3),2) >> ans = >> >> 1.0000e+00 2.0000e+00 2.0000e+00 1.0000e+00 1.3878e-17 >> >> MAtlabR11: >> » xcorr(ones(1,2),ones(1,3),2) >> >> ans = >> >> 0 1.0000 2.0000 2.0000 1.0000 > > I'd like to fix this but I am unsure if I can. See below. > >> I attach the matlab xcorr.m file if that can help. > > NEVER EVER EVER do this! This code belongs to Mathworks and not to you, > so you don't have the rights to distribute it. By distributing this file > you are violating Mathworks copyright. While I did not look at the code > you sent me off-list, I am unsure if I can look into the problem any > more. I think you're overreacting a bit, Soren. In fact, even if you did look, no law does prohibit reading, only copying. If you inspect a m-file from Matlab to learn just the trick, and don't actually memorize and reproduce any code, it's technically still legal. But in any case, you said you didn't look, so you didn't look and that settles it. Innocent until proved guilty. -- RNDr. Jaroslav Hajek computing expert & GNU Octave developer Aeronautical Research and Test Institute (VZLU) Prague, Czech Republic url: www.highegg.matfyz.cz ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Octave-dev mailing list Octave-dev@... https://lists.sourceforge.net/lists/listinfo/octave-dev |
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Re: Incompatibility MATLAB-OCTAVE : xcorr.m
by Søren Hauberg
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fre, 23 10 2009 kl. 13:02 +0200, skrev Jaroslav Hajek:
> I think you're overreacting a bit, Soren. Yeah, you're probably right. I tend to be a bit sensitive about issues such as this. While I don't agree with Mathwork's choice of distribution, I do have a great deal of respect for their choice. I also really want to send the message that nobody should be distributing Mathwork's code to Octave developers. Anyway, I probably overreacted, and for that I apologize, Søren ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Octave-dev mailing list Octave-dev@... https://lists.sourceforge.net/lists/listinfo/octave-dev |
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