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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents d0c2a83c1364
children
rev   line source
Chris@82 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@82 2 <html>
Chris@82 3 <!-- This manual is for FFTW
Chris@82 4 (version 3.3.8, 24 May 2018).
Chris@82 5
Chris@82 6 Copyright (C) 2003 Matteo Frigo.
Chris@82 7
Chris@82 8 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@82 9
Chris@82 10 Permission is granted to make and distribute verbatim copies of this
Chris@82 11 manual provided the copyright notice and this permission notice are
Chris@82 12 preserved on all copies.
Chris@82 13
Chris@82 14 Permission is granted to copy and distribute modified versions of this
Chris@82 15 manual under the conditions for verbatim copying, provided that the
Chris@82 16 entire resulting derived work is distributed under the terms of a
Chris@82 17 permission notice identical to this one.
Chris@82 18
Chris@82 19 Permission is granted to copy and distribute translations of this manual
Chris@82 20 into another language, under the above conditions for modified versions,
Chris@82 21 except that this permission notice may be stated in a translation
Chris@82 22 approved by the Free Software Foundation. -->
Chris@82 23 <!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: Precision</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Precision">
Chris@82 28 <meta name="keywords" content="FFTW 3.3.8: Precision">
Chris@82 29 <meta name="resource-type" content="document">
Chris@82 30 <meta name="distribution" content="global">
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Chris@82 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Chris@82 33 <link href="index.html#Top" rel="start" title="Top">
Chris@82 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@82 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@82 36 <link href="Data-Types-and-Files.html#Data-Types-and-Files" rel="up" title="Data Types and Files">
Chris@82 37 <link href="Memory-Allocation.html#Memory-Allocation" rel="next" title="Memory Allocation">
Chris@82 38 <link href="Complex-numbers.html#Complex-numbers" rel="prev" title="Complex numbers">
Chris@82 39 <style type="text/css">
Chris@82 40 <!--
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Chris@82 65 </style>
Chris@82 66
Chris@82 67
Chris@82 68 </head>
Chris@82 69
Chris@82 70 <body lang="en">
Chris@82 71 <a name="Precision"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 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>
Chris@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="Precision-1"></a>
Chris@82 78 <h4 class="subsection">4.1.2 Precision</h4>
Chris@82 79 <a name="index-precision-3"></a>
Chris@82 80
Chris@82 81 <p>You can install single and long-double precision versions of FFTW,
Chris@82 82 which replace <code>double</code> with <code>float</code> and <code>long double</code>,
Chris@82 83 respectively (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>). To use these
Chris@82 84 interfaces, you:
Chris@82 85 </p>
Chris@82 86 <ul>
Chris@82 87 <li> Link to the single/long-double libraries; on Unix, <code>-lfftw3f</code> or
Chris@82 88 <code>-lfftw3l</code> instead of (or in addition to) <code>-lfftw3</code>. (You
Chris@82 89 can link to the different-precision libraries simultaneously.)
Chris@82 90
Chris@82 91 </li><li> Include the <em>same</em> <code>&lt;fftw3.h&gt;</code> header file.
Chris@82 92
Chris@82 93 </li><li> Replace all lowercase instances of &lsquo;<samp>fftw_</samp>&rsquo; with &lsquo;<samp>fftwf_</samp>&rsquo; or
Chris@82 94 &lsquo;<samp>fftwl_</samp>&rsquo; for single or long-double precision, respectively.
Chris@82 95 (<code>fftw_complex</code> becomes <code>fftwf_complex</code>, <code>fftw_execute</code>
Chris@82 96 becomes <code>fftwf_execute</code>, etcetera.)
Chris@82 97
Chris@82 98 </li><li> Uppercase names, i.e. names beginning with &lsquo;<samp>FFTW_</samp>&rsquo;, remain the
Chris@82 99 same.
Chris@82 100
Chris@82 101 </li><li> Replace <code>double</code> with <code>float</code> or <code>long double</code> for
Chris@82 102 subroutine parameters.
Chris@82 103
Chris@82 104 </li></ul>
Chris@82 105
Chris@82 106 <p>Depending upon your compiler and/or hardware, <code>long double</code> may not
Chris@82 107 be any more precise than <code>double</code> (or may not be supported at all,
Chris@82 108 although it is standard in C99).
Chris@82 109 <a name="index-C99-2"></a>
Chris@82 110 </p>
Chris@82 111
Chris@82 112 <p>We also support using the nonstandard <code>__float128</code>
Chris@82 113 quadruple-precision type provided by recent versions of <code>gcc</code> on
Chris@82 114 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>).
Chris@82 115 To use this type, link with <code>-lfftw3q -lquadmath -lm</code> (the
Chris@82 116 <code>libquadmath</code> library provided by <code>gcc</code> is needed for
Chris@82 117 quadruple-precision trigonometric functions) and use &lsquo;<samp>fftwq_</samp>&rsquo;
Chris@82 118 identifiers.
Chris@82 119 </p>
Chris@82 120
Chris@82 121
Chris@82 122
Chris@82 123 </body>
Chris@82 124 </html>