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diff src/fftw-3.3.5/doc/FAQ/fftw-faq.html/section1.html @ 42:2cd0e3b3e1fd
Current fftw source
| author | Chris Cannam |
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| date | Tue, 18 Oct 2016 13:40:26 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.5/doc/FAQ/fftw-faq.html/section1.html Tue Oct 18 13:40:26 2016 +0100 @@ -0,0 +1,85 @@ +<!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> +- 30 July 2016 +</address><br> +Extracted from FFTW Frequently Asked Questions with Answers, +Copyright © 2016 Matteo Frigo and Massachusetts Institute of Technology. +</body></html>