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From: Dunx <dunx@ho...>  20100302 11:13:42

Hi, I know about the difference between pylab.psd and mlab.psd, but in theory the only difference between the returned values is: pylab.psd = 10*log10(mlab.psd) Except this is not true, there is noticeable difference: pylab.psd = 23.4962 (all these pylab.psd values are read from graph) 10*log10(mlab.psd) = 17.2852 pylab.psd = 18.8973 10*log10(mlab.psd) = 12.8149 pylab.psd = 4.92 10*log10(mlab.psd) = 2.247 These all look suspiciously out by around 2pi, although by no means exact. Any ideas? code is: pylab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) #graph x,y = mlab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) #look at x  View this message in context: http://old.nabble.com/PSDamplitudedisparitytp27754632p27754632.html Sent from the matplotlib  users mailing list archive at Nabble.com. 
From: John Hunter <jdh2358@gm...>  20100302 15:28:33

On Tue, Mar 2, 2010 at 5:13 AM, Dunx <dunx@...> wrote: > > Hi, > > I know about the difference between pylab.psd and mlab.psd, but in theory > the only difference between the returned values is: > > pylab.psd = 10*log10(mlab.psd) > > Except this is not true, there is noticeable difference: > > pylab.psd = 23.4962 (all these pylab.psd values are read from graph) > 10*log10(mlab.psd) = 17.2852 > > pylab.psd = 18.8973 > 10*log10(mlab.psd) = 12.8149 > > pylab.psd = 4.92 > 10*log10(mlab.psd) = 2.247 > > These all look suspiciously out by around 2pi, although by no means exact. > Any ideas? > > code is: > pylab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) #graph > x,y = mlab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) #look > at x What version of mpl are you using? Could you try setting your matplotlib rc parameter path.simplify to False? There is a known bug in the released version of mpl that causes path simplification to render lines improperly. Looking at the code, Axes.psd just calls mlab.psd and then plots 10*log10(pxx), so if there is a difference the most likely culprit is a rendering bug. See http://matplotlib.sourceforge.net/users/customizing.html for information on how to change your default matplotlib rc parameters. Christoph, this is a serious bug that merits a branch bugfix release ASAP. I will do the src release if you can do the win32 release. Perhaps we can find someone who can build the OSX binaries for us since my OSX box is dead. By I don't want to hold the release for want of OSX binaries since this is a recurrent and serious problem. JDH 
From: Dunx <dunx@ho...>  20100303 10:47:49

That was it Thanks :) John Hunter4 wrote: > > On Tue, Mar 2, 2010 at 5:13 AM, Dunx <dunx@...> wrote: >> >> Hi, >> >> I know about the difference between pylab.psd and mlab.psd, but in theory >> the only difference between the returned values is: >> >> pylab.psd = 10*log10(mlab.psd) >> >> Except this is not true, there is noticeable difference: >> >> pylab.psd = 23.4962 (all these pylab.psd values are read from graph) >> 10*log10(mlab.psd) = 17.2852 >> >> pylab.psd = 18.8973 >> 10*log10(mlab.psd) = 12.8149 >> >> pylab.psd = 4.92 >> 10*log10(mlab.psd) = 2.247 >> >> These all look suspiciously out by around 2pi, although by no means >> exact. >> Any ideas? >> >> code is: >> pylab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) #graph >> x,y = mlab.psd(input, NFFT=512, Fs=sampleRate, window=blackman(512)) >> #look >> at x > > What version of mpl are you using? Could you try setting your > matplotlib rc parameter path.simplify to False? There is a known bug > in the released version of mpl that causes path simplification to > render lines improperly. Looking at the code, Axes.psd just calls > mlab.psd and then plots 10*log10(pxx), so if there is a difference the > most likely culprit is a rendering bug. > See http://matplotlib.sourceforge.net/users/customizing.html for > information on how to change your default matplotlib rc parameters. > > Christoph, this is a serious bug that merits a branch bugfix release > ASAP. I will do the src release if you can do the win32 release. > Perhaps we can find someone who can build the OSX binaries for us > since my OSX box is dead. By I don't want to hold the release for > want of OSX binaries since this is a recurrent and serious problem. > > JDH > >  > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and finetune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intelswdev > _______________________________________________ > Matplotlibusers mailing list > Matplotlibusers@... > https://lists.sourceforge.net/lists/listinfo/matplotlibusers > >  View this message in context: http://old.nabble.com/PSDamplitudedisparitytp27754632p27766635.html Sent from the matplotlib  users mailing list archive at Nabble.com. 
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