Chris@19:
Chris@19: FFTW is a free collection of fast C routines for computing the
Chris@19: Discrete Fourier Transform in one or more dimensions. It includes
Chris@19: complex, real, symmetric, and parallel transforms, and can handle
Chris@19: arbitrary array sizes efficiently. FFTW is typically faster than
Chris@19: other publically-available FFT implementations, and is even
Chris@19: competitive with vendor-tuned libraries. (See our web page for
Chris@19: extensive benchmarks.) To achieve this performance, FFTW uses novel
Chris@19: code-generation and runtime self-optimization techniques (along with
Chris@19: many other tricks).
Chris@19:
Chris@19:
Chris@19: Starting with version 1.3, FFTW is Free Software in the technical
Chris@19: sense defined by the Free Software Foundation (see
Chris@19: 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@19: distributed without fee for noncommercial use, but were not
Chris@19: technically ``free.''
Chris@19:
Chris@19: Non-free licenses for FFTW are also available that permit different
Chris@19: terms of use than the GPL.
Chris@19:
Chris@19:
Chris@19: The non-free licenses are for companies that wish to use FFTW in their
Chris@19: products but are unwilling to release their software under the GPL
Chris@19: (which would require them to release source code and allow free
Chris@19: redistribution). Such users can purchase an unlimited-use license
Chris@19: from MIT. Contact us for more details.
Chris@19:
Chris@19:
Chris@19: We could instead have released FFTW under the LGPL, or even disallowed
Chris@19: non-Free usage. Suffice it to say, however, that MIT owns the
Chris@19: copyright to FFTW and they only let us GPL it because we convinced
Chris@19: them that it would neither affect their licensing revenue nor irritate
Chris@19: existing licensees.
Chris@19:
Chris@19:
Chris@19: Not to an Italian. You could say that we're a Spaghetti Western
Chris@19: (with apologies to Sergio Leone).
Chris@19: Next: Installing FFTW.
Chris@19: Return to contents.