FFTW FAQ - Section 1
Introduction and General Information


Question 1.1. What is FFTW ?

FFTW is a collection of fast C routines for computing the Discrete Fourier Transform in one or more dimensions. FFTW is unique in two respects. First, it is not just optimized for arrays whose sizes are powers of 2, 3, or other small numbers. Instead, FFTW comes with a code generator that produces C programs for any particular array size you may care about. Second, it doesn't use a fixed strategy for performing the transform. There are usually many ways to decompose a big problem into small problems, and the optimal way often depends on many unpredictable factors. Unlike other programs, FFTW can find the optimal decomposition at runtime for the machine it is running on.

Question 1.2. How do I obtain FFTW?

FFTW can be found at the FFTW web page. You can also retrieve it from theory.lcs.mit.edu in /pub/fftw.

As of the present date, the latest version is 1.2.

Question 1.3. Is FFTW free software?

FFTW is free for non-commercial use. In other words, you can use it for fun, educational purposes, or for internal development. You cannot incorporate FFTW into a commercial product.

The FFTW copyright is held by the Massachusetts Institute of Technology (MIT). Commercial licenses are available. Please contact the authors if you are interested in using FFTW in a commercial product.


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Matteo Frigo and Steven G. Johnson / fftw@theory.lcs.mit.edu - 08 September 1997

Extracted from FFTW Frequently Asked Questions with Answers, Copyright © 1997 Massachusetts Institute of Technology.