From bug-request at octave dot org Fri Oct 8 09:53:14 2004 Subject: Re: Memory Corruption? From: David Bateman To: Quentin Spencer Cc: bug at octave dot org Date: Fri, 8 Oct 2004 16:49:11 +0200 Ok, so something is being corruptted. Its either * Something to do with the variable r, * Something to do with Fifft, or * Something to do with the use of FFTW. I suspect its the last one, and there my_function is an oct-file that is doing something weird... A way to check if the FFTW plan is messed up is something like the following r=rand(1,256); mean(real(fft(r))./real(ifft(r))) my_function; s = rand(1,1024); mean(real(fft(s))./real(ifft(s))) mean(real(fft(r))./real(ifft(r))) The call to a different FFT size will cause octave to create a new FFTW plan, and then recreate the FFTW plan for the 256 point IFFT... In any case if you can get a minimum version of my_function that causes this problem I'd be interested in having a copy... Regards D. According to Quentin Spencer (on 10/08/04): > David Bateman wrote: > > >Do you have FFTW installed? What does > > > >octave_config_info ("FFTW_LIBS") > > > > > octave:1> octave_config_info ("FFTW_LIBS") > ans = -lfftw3 > octave:2> r=rand(1,256); > octave:3> mean(real(fft(r))./real(ifft(r))) > ans = 256.00 > octave:4> my_function; > octave:5> mean(real(fft(r))./real(ifft(r))) > ans = 3.5356 > > It appears that in the process of running my simulation, ifft gets > corrupted and returns a different answer on the same data. > > > > ------------------------------------------------------------- > Octave is freely available under the terms of the GNU GPL. > > Octave's home on the web: http://www.octave.org > How to fund new projects: http://www.octave.org/funding.html > Subscription information: http://www.octave.org/archive.html > ------------------------------------------------------------- -- David Bateman David dot Bateman at motorola dot com Motorola CRM +33 1 69 35 48 04 (Ph) Parc Les Algorithmes, Commune de St Aubin +33 1 69 35 77 01 (Fax) 91193 Gif-Sur-Yvette FRANCE The information contained in this communication has been classified as: [x] General Business Information [ ] Motorola Internal Use Only [ ] Motorola Confidential Proprietary ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------