[SciPy-dev] Question about fft overwrites; still scipy.fft problem on OS X

Tom Loredo loredo at astro.cornell.edu
Tue Jan 10 15:10:02 CST 2006


Hi folks,

The current scipy checkout (1544) and numpy 1863 and 1864 both
produce "Overwriting fft" and "Overwriting ifft" warnings
when scipy is imported.  This happens both on FC3 and on OS X
(10.3.9), so I presume it's not unique to my machines.  Is
this anything I need to worry about?  I have to freeze
a numpy/scipy tarball tomorrow for a sysadmin who has to
install them on student machines; I'll just tell him and
the students that the warning is innocuous, if it really is.

scipy's fft/ifft (scipy.fft, scipy.ifft) still give erroneous
results on OS X, though not on FC3 (both with recent installs
of FFTW2).  numpy.fft works fine on both platforms, so I'll
have my students stick with that.  scipy.fft worked fine on
OS X last week....

from scipy import *
x = arange(16)*2*pi/16
sx = sin(x)
sfx = fft(sx)
sfix = ifft(sfx)
print max(abs(sx-sfix.real))

On OS X Panther this prints "1.0"; change "scipy" to "numpy" and
it prints "1.11e-16" (or thereabouts).  On FC3, both work fine.

FYI, the bug I reported earlier regarding f2py-wrapped
functions with float arguments having trouble accepting
scalar arrays has vanished over the weekend (on both
platforms).  I don't know what changed to fix this, but I'm
glad of it---thanks to whomever!

-Tom




More information about the Scipy-dev mailing list