On 11/18/2011 01:18 PM, Dag Sverre Seljebotn wrote: > On 11/18/2011 12:58 PM, David Cournapeau wrote: >> On Fri, Nov 18, 2011 at 11:42 AM, Robert Kern<[email protected]> wrote: >>> On Fri, Nov 18, 2011 at 11:19, Dag Sverre Seljebotn >>> <[email protected]> wrote: >>>> I've been in touch with Martin Reinecke, author of the libpsht code for >>>> spherical harmonic transforms, about licensing issues. >>>> >>>> libpsht itself will remain under the GPL, but he is likely to release >>>> his C port of FFTPACK under BSD in the near future, as it is based on >>>> the public domain FFTPACK. >>>> >>>> I'm grateful for this change for my own purposes (allows releasing my >>>> own competing SHT library under the BSD) -- but it could perhaps be >>>> useful for NumPy or SciPy as well, depending on how complete the port >>>> is? E.g., perhaps make numpy.fft more complete (is the >>>> numpy.fft/scipy.fftpack split simply because of the Fortran dependency?). >>> >>> It used to be the case that scipy.fftpack allowed one to build against >>> multiple different, usually faster, FFT libraries like FFTW. I think >>> we have backed away from that since the cost of maintaining the build >>> configuration for all of those different backends was so high. It's >>> worth noting that numpy.fft is already using a C translation of >>> FFTPACK. I'm not sure what the differences are between this >>> translation and Martin's. > > Here's some more info forwarded from Martin: > > """ > - only FFTs are supported (no DCTs/DSTs) > - only double precision is supported (extension to single precision might > not be much work, though) > - both complex and real FFTs are supported > - real FFTs allow various storage schemes for the (half)complex frequency > domain data (classic FFTPACK scheme, FFTW or halfcomplex scheme, > uncompressed complex storage) > - precision of transforms involving large prime factors should be slightly > better than with original FFTPACK > - Bluestein's algorithm is automatically selected if considered profitable > - small accuracy self-testing code is provided. > > Fairly complete interface documentation is available in Doxygen format. > I'll prepare a source package later in the afternoon and send it around.
OK, Martin sent me a BSD-ed version of his libfftpack, and I stuck it on github: https://github.com/dagss/libfftpack Note that ls_fft.h contains Martin's API for it (plan construction and execution etc.) Dag Sverre _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
