[SciPy-User] silently different results when running scipy.signal.fftconvolve on ubuntu karmic vs. lucid

[Pauli Virtanen]

Wed, 26 Jan 2011 15:20:05 +0100, Ábel Dániel wrote:
> About a week ago I wrote about an issue with using
> scipy.signal.fftconvolve and scipy.signal.correlate2d.  I hit another
> issue since: apparently scipy.signal.fftconvolve gives different results
> under ubuntu karmic and ubuntu lucid. I assume this is due to some small
> difference in the versions of the libraries used by the two, I alread
> submitted a bugreport to ubuntu's bugtracker
> (https://bugs.launchpad.net/ubuntu/+source/python-scipy/+bug/705354)
> 
> Since that report didn't get any reaction, I thought I would ask here,
> as well: any idea what might be causing this difference?
[clip]

Ubuntu Karmic and Lucid have the *same* versions of Numpy and Scipy, 
1.3.0 and 0.7.0:

	http://packages.ubuntu.com/search?keywords=python-scipy
	http://packages.ubuntu.com/search?keywords=python-numpy

Seems hardly possible that it can be an issue with Numpy/Scipy.

Probably the image package you used to save the images had bugs
with dealing with arrays, as its version is different:

	http://packages.ubuntu.com/search?keywords=python-imaging

Did you check that the actual numerical contents of the arrays disagree?
(Try saving the results with numpy.savez to compare across machines.)

-- 
Pauli Virtanen