Chris@42:
Chris@42: FFTW is a free collection of fast C routines for computing the
Chris@42: Discrete Fourier Transform in one or more dimensions. It includes
Chris@42: complex, real, symmetric, and parallel transforms, and can handle
Chris@42: arbitrary array sizes efficiently. FFTW is typically faster than
Chris@42: other publically-available FFT implementations, and is even
Chris@42: competitive with vendor-tuned libraries. (See our web page for
Chris@42: extensive benchmarks.) To achieve this performance, FFTW uses novel
Chris@42: code-generation and runtime self-optimization techniques (along with
Chris@42: many other tricks).
Chris@42:
Chris@42:
Chris@42: Starting with version 1.3, FFTW is Free Software in the technical
Chris@42: sense defined by the Free Software Foundation (see
Chris@42: Categories of Free and Non-Free Software), and is distributed under the terms of the GNU General Public License. Previous versions of FFTW were
Chris@42: distributed without fee for noncommercial use, but were not
Chris@42: technically ``free.''
Chris@42:
Chris@42: Non-free licenses for FFTW are also available that permit different
Chris@42: terms of use than the GPL.
Chris@42:
Chris@42:
Chris@42: The non-free licenses are for companies that wish to use FFTW in their
Chris@42: products but are unwilling to release their software under the GPL
Chris@42: (which would require them to release source code and allow free
Chris@42: redistribution). Such users can purchase an unlimited-use license
Chris@42: from MIT. Contact us for more details.
Chris@42:
Chris@42:
Chris@42: We could instead have released FFTW under the LGPL, or even disallowed
Chris@42: non-Free usage. Suffice it to say, however, that MIT owns the
Chris@42: copyright to FFTW and they only let us GPL it because we convinced
Chris@42: them that it would neither affect their licensing revenue nor irritate
Chris@42: existing licensees.
Chris@42:
Chris@42:
Chris@42: Not to an Italian. You could say that we're a Spaghetti Western
Chris@42: (with apologies to Sergio Leone).
Chris@42: Next: Installing FFTW.
Chris@42: Return to contents.