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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Nov 2019 14:52:55 +0000
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cannam@167 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
cannam@167 2 <html>
cannam@167 3 <!-- This manual is for FFTW
cannam@167 4 (version 3.3.8, 24 May 2018).
cannam@167 5
cannam@167 6 Copyright (C) 2003 Matteo Frigo.
cannam@167 7
cannam@167 8 Copyright (C) 2003 Massachusetts Institute of Technology.
cannam@167 9
cannam@167 10 Permission is granted to make and distribute verbatim copies of this
cannam@167 11 manual provided the copyright notice and this permission notice are
cannam@167 12 preserved on all copies.
cannam@167 13
cannam@167 14 Permission is granted to copy and distribute modified versions of this
cannam@167 15 manual under the conditions for verbatim copying, provided that the
cannam@167 16 entire resulting derived work is distributed under the terms of a
cannam@167 17 permission notice identical to this one.
cannam@167 18
cannam@167 19 Permission is granted to copy and distribute translations of this manual
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cannam@167 22 approved by the Free Software Foundation. -->
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cannam@167 24 <head>
cannam@167 25 <title>FFTW 3.3.8: Precision</title>
cannam@167 26
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cannam@167 37 <link href="Memory-Allocation.html#Memory-Allocation" rel="next" title="Memory Allocation">
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cannam@167 68 </head>
cannam@167 69
cannam@167 70 <body lang="en">
cannam@167 71 <a name="Precision"></a>
cannam@167 72 <div class="header">
cannam@167 73 <p>
cannam@167 74 Next: <a href="Memory-Allocation.html#Memory-Allocation" accesskey="n" rel="next">Memory Allocation</a>, Previous: <a href="Complex-numbers.html#Complex-numbers" accesskey="p" rel="prev">Complex numbers</a>, Up: <a href="Data-Types-and-Files.html#Data-Types-and-Files" accesskey="u" rel="up">Data Types and Files</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
cannam@167 75 </div>
cannam@167 76 <hr>
cannam@167 77 <a name="Precision-1"></a>
cannam@167 78 <h4 class="subsection">4.1.2 Precision</h4>
cannam@167 79 <a name="index-precision-3"></a>
cannam@167 80
cannam@167 81 <p>You can install single and long-double precision versions of FFTW,
cannam@167 82 which replace <code>double</code> with <code>float</code> and <code>long double</code>,
cannam@167 83 respectively (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>). To use these
cannam@167 84 interfaces, you:
cannam@167 85 </p>
cannam@167 86 <ul>
cannam@167 87 <li> Link to the single/long-double libraries; on Unix, <code>-lfftw3f</code> or
cannam@167 88 <code>-lfftw3l</code> instead of (or in addition to) <code>-lfftw3</code>. (You
cannam@167 89 can link to the different-precision libraries simultaneously.)
cannam@167 90
cannam@167 91 </li><li> Include the <em>same</em> <code>&lt;fftw3.h&gt;</code> header file.
cannam@167 92
cannam@167 93 </li><li> Replace all lowercase instances of &lsquo;<samp>fftw_</samp>&rsquo; with &lsquo;<samp>fftwf_</samp>&rsquo; or
cannam@167 94 &lsquo;<samp>fftwl_</samp>&rsquo; for single or long-double precision, respectively.
cannam@167 95 (<code>fftw_complex</code> becomes <code>fftwf_complex</code>, <code>fftw_execute</code>
cannam@167 96 becomes <code>fftwf_execute</code>, etcetera.)
cannam@167 97
cannam@167 98 </li><li> Uppercase names, i.e. names beginning with &lsquo;<samp>FFTW_</samp>&rsquo;, remain the
cannam@167 99 same.
cannam@167 100
cannam@167 101 </li><li> Replace <code>double</code> with <code>float</code> or <code>long double</code> for
cannam@167 102 subroutine parameters.
cannam@167 103
cannam@167 104 </li></ul>
cannam@167 105
cannam@167 106 <p>Depending upon your compiler and/or hardware, <code>long double</code> may not
cannam@167 107 be any more precise than <code>double</code> (or may not be supported at all,
cannam@167 108 although it is standard in C99).
cannam@167 109 <a name="index-C99-2"></a>
cannam@167 110 </p>
cannam@167 111
cannam@167 112 <p>We also support using the nonstandard <code>__float128</code>
cannam@167 113 quadruple-precision type provided by recent versions of <code>gcc</code> on
cannam@167 114 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>).
cannam@167 115 To use this type, link with <code>-lfftw3q -lquadmath -lm</code> (the
cannam@167 116 <code>libquadmath</code> library provided by <code>gcc</code> is needed for
cannam@167 117 quadruple-precision trigonometric functions) and use &lsquo;<samp>fftwq_</samp>&rsquo;
cannam@167 118 identifiers.
cannam@167 119 </p>
cannam@167 120
cannam@167 121
cannam@167 122
cannam@167 123 </body>
cannam@167 124 </html>