On Thu, Apr 19, 2007 at 05:46:49PM -0400, Al Falloon wrote:
For us less knowledgable, what's fftw?
"Fastest Fourier Transform in the West." http://www.fftw.org/
Its cool, they use generative programming: an OCaml program generates "codlets" in C that can be composed and tuned to the specifics of your machine, then compiled into a blazingly fast FFT/DFT library.
But that's only the beginning of the coolness! fftw uses runtime timings to optimize each fourier transform based on the behavior of the computer on which it is being run--its cache, memory speed, CPU, etc. The result being that fftw using portable C can beat out most hand-optimized fftw libraries written in assembly! Steven (one of fftw's two authors) has done some incredible work on optimizations. The most unbelievable (to me) was that by eliminating negative constants from the generated code (using subtraction instead) they sped up the library on a particular architecture by some some significant margin (I think I recall 20%). -- David Roundy http://www.darcs.net