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.
Having a Bluestein transformation alone would be worthwhile, as it would avoid the N^2 penalty for prime sizes. I am wondering about precision issues, though (when I tried implementing bluestein transforms on top of fftpack, it gave very bad results numerically-wise). A comparison with fftw would be good here. regards, David _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
