Hi all,
Can anyone tell me if fftpack_lite is an exact C translation of the fftpack Fortran code? Or at least close enough that the signature, parameter descriptions and algorithm are the same?
If so, I can use the fftpack Fortran sources (which have useful comments) to write docs for fftpack_lite funcs (rfft* and cfft*).
Thanks, Ralf
On Sun, Oct 25, 2009 at 4:21 PM, Ralf Gommers ralf.gommers@googlemail.comwrote:
Hi all,
Can anyone tell me if fftpack_lite is an exact C translation of the fftpack Fortran code? Or at least close enough that the signature, parameter descriptions and algorithm are the same?
If so, I can use the fftpack Fortran sources (which have useful comments) to write docs for fftpack_lite funcs (rfft* and cfft*).
fft_pack is an interface to a c translation of fftpack. IIRC, it adds some stuff like zerofill and such so it isn't a1-1 matchup. I think it is pretty close, though.
Chuck
On Sun, Oct 25, 2009 at 11:51 PM, Charles R Harris < charlesr.harris@gmail.com> wrote:
On Sun, Oct 25, 2009 at 4:21 PM, Ralf Gommers <ralf.gommers@googlemail.com
wrote:
Hi all,
Can anyone tell me if fftpack_lite is an exact C translation of the fftpack Fortran code? Or at least close enough that the signature, parameter descriptions and algorithm are the same?
If so, I can use the fftpack Fortran sources (which have useful comments) to write docs for fftpack_lite funcs (rfft* and cfft*).
fft_pack is an interface to a c translation of fftpack. IIRC, it adds some stuff like zerofill and such so it isn't a1-1 matchup. I think it is pretty close, though.
Okay, thanks. I'll start with the Fortran docs then, and someone familiar with the differences could then easily throw in a few notes on that.
Ralf
Chuck
NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
On Mon, Oct 26, 2009 at 12:04 AM, Ralf Gommers ralf.gommers@googlemail.comwrote:
On Sun, Oct 25, 2009 at 11:51 PM, Charles R Harris < charlesr.harris@gmail.com> wrote:
On Sun, Oct 25, 2009 at 4:21 PM, Ralf Gommers < ralf.gommers@googlemail.com> wrote:
Hi all,
Can anyone tell me if fftpack_lite is an exact C translation of the fftpack Fortran code? Or at least close enough that the signature, parameter descriptions and algorithm are the same?
If so, I can use the fftpack Fortran sources (which have useful comments) to write docs for fftpack_lite funcs (rfft* and cfft*).
fft_pack is an interface to a c translation of fftpack. IIRC, it adds some stuff like zerofill and such so it isn't a1-1 matchup. I think it is pretty close, though.
Okay, thanks. I'll start with the Fortran docs then, and someone familiar with the differences could then easily throw in a few notes on that.
There are docs now for all six exposed functions (cfft*, rfft*):
http://docs.scipy.org/numpy/docs/numpy.fft.fftpack_lite/
If anyone with knowledge of the differences between the C and Fortran versions could add a few notes at the above link, that would be great.
Thanks, Ralf
Ralf Gommers skrev:
If anyone with knowledge of the differences between the C and Fortran versions could add a few notes at the above link, that would be great.
The most notable difference (from a user perspective) is that the Fortran version has more transforms, such as discrete sine and cosine transforms. It also supports single and double precision. The older Fortran version is used in SciPy.
FFTs from FFTW and MKL tend to be faster than FFTPACK, at least on Intel hardware. FFTPACK was originally written for running fast on vector machines like the Cray and NEC.
FFTPACK-lite: http://projects.scipy.org/numpy/browser/trunk/scipy/basic/fftpack_lite?rev=1...
Older Fortran version: http://www.netlib.org/fftpack/
Fortran 90 version (no license): http://orion.math.iastate.edu/burkardt/f_src/fftpack/fftpack.html
Another C version: http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=fftpac... http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=fftpack/fft.c
S.M.
Hi Sturla,
Thanks for the overview.
On Mon, Oct 26, 2009 at 5:24 PM, Sturla Molden sturla@molden.no wrote:
Ralf Gommers skrev:
If anyone with knowledge of the differences between the C and Fortran versions could add a few notes at the above link, that would be great.
The most notable difference (from a user perspective) is that the Fortran version has more transforms, such as discrete sine and cosine transforms. It also supports single and double precision. The older Fortran version is used in SciPy.
I added this to the module docstring.
The info that would still be useful is how the functions that are exposed in fftpack_lite are subtly different from the older Fortran functions. Charles mentioned zerofill for example. Those funcs are: cfftb cfftf cffti rfftb rfftf rffti
Cheers, Ralf