Question for the HP guys.... - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Question for the HP guys.... (/thread-9258.html) |
Question for the HP guys.... - webmasterpdx - 10-08-2017 11:37 PM I remember from back in my supercomputer days, the FFT algorithm was pretty important in the field I worked in, and there were generally 2 ways to implement it. The first used bit-reverse and radix-2 transform, while the second used digit-reverse and radix-4 transform. Radix-4 was quite a bit faster in implementation, so what I'm wondering is which is the version of the FFT function on the HP Prime, radix-2 or radix-4 ????????? Thanks -Donald RE: Question for the HP guys.... - Tim Wessman - 10-09-2017 12:03 AM https://www-fourier.ujf-grenoble.fr/~parisse/giac_compile.html You'll be able to find it just as fast I think. Download the source, search for "fft" and you'll probably find it. Bernard might chime in. RE: Question for the HP guys.... - Mark Hardman - 10-09-2017 12:30 AM (10-09-2017 12:03 AM)Tim Wessman Wrote: Download the source, search for "fft" and you'll probably find it. Bernard might chime in. https://www-fourier.ujf-grenoble.fr/~parisse/giac/src/modpoly.cc Around line 3171: Code: // Fast Fourier Transform, f the poly sum_{j<n} f_j x^j, RE: Question for the HP guys.... - webmasterpdx - 10-09-2017 04:25 AM I looked through the source code and from what I can tell, in maple.cc, if HP uses gcc and libgsl (Gnu Scientific Library), then they call the radix2 transform function. Anyway, radix 4 speed increases are only significant when a large number of data elements are being used and since we are talking about a calculator, it's doubtful if large numbers of data elements are going to be used in fft's. Thus the advantage of a radix-4 would be minimal in any case. Good 'nuff... :-) Thx -Donald RE: Question for the HP guys.... - parisse - 10-10-2017 09:09 AM The GSL is not active when giac is compiled for the Prime. There are two main FFT implementations, one for complex<double> data, and one for modular integers. The first one has prototype Code: void fft(std::complex<double> * f,int n,const std::complex<double> * w,int m,complex< double> * t) |