mirror of
https://github.com/tildearrow/furnace.git
synced 2024-11-06 12:55:05 +00:00
85 lines
3.6 KiB
HTML
85 lines
3.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
|
|
<html>
|
|
<head><title>
|
|
FFTW FAQ - Section 1
|
|
</title>
|
|
<link rev="made" href="mailto:fftw@fftw.org">
|
|
<link rel="Contents" href="index.html">
|
|
<link rel="Start" href="index.html">
|
|
<link rel="Next" href="section2.html"><link rel="Bookmark" title="FFTW FAQ" href="index.html">
|
|
</head><body text="#000000" bgcolor="#FFFFFF"><h1>
|
|
FFTW FAQ - Section 1 <br>
|
|
Introduction and General Information
|
|
</h1>
|
|
|
|
<ul>
|
|
<li><a href="#whatisfftw" rel=subdocument>Q1.1. What is FFTW?</a>
|
|
<li><a href="#whereisfftw" rel=subdocument>Q1.2. How do I obtain FFTW?</a>
|
|
<li><a href="#isfftwfree" rel=subdocument>Q1.3. Is FFTW free software?</a>
|
|
<li><a href="#nonfree" rel=subdocument>Q1.4. What is this about non-free licenses?</a>
|
|
<li><a href="#west" rel=subdocument>Q1.5. In the West? I thought MIT was in the East?</a>
|
|
</ul><hr>
|
|
|
|
<h2><A name="whatisfftw">
|
|
Question 1.1. What is FFTW?
|
|
</A></h2>
|
|
|
|
FFTW is a free collection of fast C routines for computing the
|
|
Discrete Fourier Transform in one or more dimensions. It includes
|
|
complex, real, symmetric, and parallel transforms, and can handle
|
|
arbitrary array sizes efficiently. FFTW is typically faster than
|
|
other publically-available FFT implementations, and is even
|
|
competitive with vendor-tuned libraries. (See our web page for
|
|
extensive benchmarks.) To achieve this performance, FFTW uses novel
|
|
code-generation and runtime self-optimization techniques (along with
|
|
many other tricks).
|
|
<h2><A name="whereisfftw">
|
|
Question 1.2. How do I obtain FFTW?
|
|
</A></h2>
|
|
|
|
FFTW can be found at <A href="http://www.fftw.org">the FFTW web page</A>. You can also retrieve it from <code>ftp.fftw.org</code> in <A href="ftp://ftp.fftw.org/pub/fftw"><code>/pub/fftw</code></A>.
|
|
<h2><A name="isfftwfree">
|
|
Question 1.3. Is FFTW free software?
|
|
</A></h2>
|
|
|
|
Starting with version 1.3, FFTW is Free Software in the technical
|
|
sense defined by the Free Software Foundation (see
|
|
<A href="http://www.gnu.org/philosophy/categories.html">Categories of Free and Non-Free Software</A>), and is distributed under the terms of the GNU General Public License. Previous versions of FFTW were
|
|
distributed without fee for noncommercial use, but were not
|
|
technically ``free.''
|
|
<p>
|
|
Non-free licenses for FFTW are also available that permit different
|
|
terms of use than the GPL.
|
|
<h2><A name="nonfree">
|
|
Question 1.4. What is this about non-free
|
|
licenses?
|
|
</A></h2>
|
|
|
|
The non-free licenses are for companies that wish to use FFTW in their
|
|
products but are unwilling to release their software under the GPL
|
|
(which would require them to release source code and allow free
|
|
redistribution). Such users can purchase an unlimited-use license
|
|
from MIT. Contact us for more details.
|
|
|
|
<p>
|
|
We could instead have released FFTW under the LGPL, or even disallowed
|
|
non-Free usage. Suffice it to say, however, that MIT owns the
|
|
copyright to FFTW and they only let us GPL it because we convinced
|
|
them that it would neither affect their licensing revenue nor irritate
|
|
existing licensees.
|
|
<h2><A name="west">
|
|
Question 1.5. In the West? I thought MIT was in the
|
|
East?
|
|
</A></h2>
|
|
|
|
Not to an Italian. You could say that we're a Spaghetti Western
|
|
(with apologies to Sergio Leone). <hr>
|
|
Next: <a href="section2.html" rel=precedes>Installing FFTW</a>.<br>
|
|
<a href="index.html" rev=subdocument>Return to contents</a>.<p>
|
|
<address>
|
|
<A href="http://www.fftw.org">Matteo Frigo and Steven G. Johnson</A> / <A href="mailto:fftw@fftw.org">fftw@fftw.org</A>
|
|
- 14 September 2021
|
|
</address><br>
|
|
Extracted from FFTW Frequently Asked Questions with Answers,
|
|
Copyright © 2021 Matteo Frigo and Massachusetts Institute of Technology.
|
|
</body></html>
|