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[Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for
From: |
Mark van Rossum |
Subject: |
[Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets |
Date: |
Fri, 19 Feb 2021 07:21:59 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.182 Safari/537.36 |
Follow-up Comment #5, bug #60076 (project octave):
Thank you Dmitri, I thought I was going crazy.
I see the bug on Ubuntu 20.04, but not on a different system with Debian 10.
Here is the core of the xcorr.m code.
%%%% xcorr.m code:
M = 2^nextpow2(N + maxlag)
post = fft( postpad(X(:),M) );
cor = ifft( post .* conj(post) );
R = [ conj(cor(maxlag+1:-1:2)) ; cor(1:maxlag+1) ];
Whenever the data length surpasses 4096, the ftt behaves oddly.
R gets large imaginary components, which should not happen.
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- [Octave-bug-tracker] [bug #60076] signal xcorr bug for large datasets, Mark van Rossum, 2021/02/18
- [Octave-bug-tracker] [bug #60076] signal xcorr bug for large datasets, Mark van Rossum, 2021/02/18
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Kai Torben Ohlhus, 2021/02/18
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Philip Nienhuis, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Mark van Rossum, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Dmitri A. Sergatskov, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets,
Mark van Rossum <=
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Dmitri A. Sergatskov, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Mark van Rossum, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Philip Nienhuis, 2021/02/19
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Mark van Rossum, 2021/02/20
- [Octave-bug-tracker] [bug #60076] [octave forge] (signal) xcorr bug for large datasets, Philip Nienhuis, 2021/02/20