Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.5/doc/html/Precision.html @ 42:2cd0e3b3e1fd

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Current fftw source
author Chris Cannam
date Tue, 18 Oct 2016 13:40:26 +0100
parents
children
rev   line source
Chris@42 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@42 2 <html>
Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
Chris@42 5
Chris@42 6 Copyright (C) 2003 Matteo Frigo.
Chris@42 7
Chris@42 8 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@42 9
Chris@42 10 Permission is granted to make and distribute verbatim copies of this
Chris@42 11 manual provided the copyright notice and this permission notice are
Chris@42 12 preserved on all copies.
Chris@42 13
Chris@42 14 Permission is granted to copy and distribute modified versions of this
Chris@42 15 manual under the conditions for verbatim copying, provided that the
Chris@42 16 entire resulting derived work is distributed under the terms of a
Chris@42 17 permission notice identical to this one.
Chris@42 18
Chris@42 19 Permission is granted to copy and distribute translations of this manual
Chris@42 20 into another language, under the above conditions for modified versions,
Chris@42 21 except that this permission notice may be stated in a translation
Chris@42 22 approved by the Free Software Foundation. -->
Chris@42 23 <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Precision</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Precision">
Chris@42 28 <meta name="keywords" content="FFTW 3.3.5: Precision">
Chris@42 29 <meta name="resource-type" content="document">
Chris@42 30 <meta name="distribution" content="global">
Chris@42 31 <meta name="Generator" content="makeinfo">
Chris@42 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Chris@42 33 <link href="index.html#Top" rel="start" title="Top">
Chris@42 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Data-Types-and-Files.html#Data-Types-and-Files" rel="up" title="Data Types and Files">
Chris@42 37 <link href="Memory-Allocation.html#Memory-Allocation" rel="next" title="Memory Allocation">
Chris@42 38 <link href="Complex-numbers.html#Complex-numbers" rel="prev" title="Complex numbers">
Chris@42 39 <style type="text/css">
Chris@42 40 <!--
Chris@42 41 a.summary-letter {text-decoration: none}
Chris@42 42 blockquote.smallquotation {font-size: smaller}
Chris@42 43 div.display {margin-left: 3.2em}
Chris@42 44 div.example {margin-left: 3.2em}
Chris@42 45 div.indentedblock {margin-left: 3.2em}
Chris@42 46 div.lisp {margin-left: 3.2em}
Chris@42 47 div.smalldisplay {margin-left: 3.2em}
Chris@42 48 div.smallexample {margin-left: 3.2em}
Chris@42 49 div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
Chris@42 50 div.smalllisp {margin-left: 3.2em}
Chris@42 51 kbd {font-style:oblique}
Chris@42 52 pre.display {font-family: inherit}
Chris@42 53 pre.format {font-family: inherit}
Chris@42 54 pre.menu-comment {font-family: serif}
Chris@42 55 pre.menu-preformatted {font-family: serif}
Chris@42 56 pre.smalldisplay {font-family: inherit; font-size: smaller}
Chris@42 57 pre.smallexample {font-size: smaller}
Chris@42 58 pre.smallformat {font-family: inherit; font-size: smaller}
Chris@42 59 pre.smalllisp {font-size: smaller}
Chris@42 60 span.nocodebreak {white-space:nowrap}
Chris@42 61 span.nolinebreak {white-space:nowrap}
Chris@42 62 span.roman {font-family:serif; font-weight:normal}
Chris@42 63 span.sansserif {font-family:sans-serif; font-weight:normal}
Chris@42 64 ul.no-bullet {list-style: none}
Chris@42 65 -->
Chris@42 66 </style>
Chris@42 67
Chris@42 68
Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Precision"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 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@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Precision-1"></a>
Chris@42 79 <h4 class="subsection">4.1.2 Precision</h4>
Chris@42 80 <a name="index-precision-3"></a>
Chris@42 81
Chris@42 82 <p>You can install single and long-double precision versions of FFTW,
Chris@42 83 which replace <code>double</code> with <code>float</code> and <code>long double</code>,
Chris@42 84 respectively (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>). To use these
Chris@42 85 interfaces, you:
Chris@42 86 </p>
Chris@42 87 <ul>
Chris@42 88 <li> Link to the single/long-double libraries; on Unix, <code>-lfftw3f</code> or
Chris@42 89 <code>-lfftw3l</code> instead of (or in addition to) <code>-lfftw3</code>. (You
Chris@42 90 can link to the different-precision libraries simultaneously.)
Chris@42 91
Chris@42 92 </li><li> Include the <em>same</em> <code>&lt;fftw3.h&gt;</code> header file.
Chris@42 93
Chris@42 94 </li><li> Replace all lowercase instances of &lsquo;<samp>fftw_</samp>&rsquo; with &lsquo;<samp>fftwf_</samp>&rsquo; or
Chris@42 95 &lsquo;<samp>fftwl_</samp>&rsquo; for single or long-double precision, respectively.
Chris@42 96 (<code>fftw_complex</code> becomes <code>fftwf_complex</code>, <code>fftw_execute</code>
Chris@42 97 becomes <code>fftwf_execute</code>, etcetera.)
Chris@42 98
Chris@42 99 </li><li> Uppercase names, i.e. names beginning with &lsquo;<samp>FFTW_</samp>&rsquo;, remain the
Chris@42 100 same.
Chris@42 101
Chris@42 102 </li><li> Replace <code>double</code> with <code>float</code> or <code>long double</code> for
Chris@42 103 subroutine parameters.
Chris@42 104
Chris@42 105 </li></ul>
Chris@42 106
Chris@42 107 <p>Depending upon your compiler and/or hardware, <code>long double</code> may not
Chris@42 108 be any more precise than <code>double</code> (or may not be supported at all,
Chris@42 109 although it is standard in C99).
Chris@42 110 <a name="index-C99-2"></a>
Chris@42 111 </p>
Chris@42 112
Chris@42 113 <p>We also support using the nonstandard <code>__float128</code>
Chris@42 114 quadruple-precision type provided by recent versions of <code>gcc</code> on
Chris@42 115 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>).
Chris@42 116 To use this type, link with <code>-lfftw3q -lquadmath -lm</code> (the
Chris@42 117 <code>libquadmath</code> library provided by <code>gcc</code> is needed for
Chris@42 118 quadruple-precision trigonometric functions) and use &lsquo;<samp>fftwq_</samp>&rsquo;
Chris@42 119 identifiers.
Chris@42 120 </p>
Chris@42 121
Chris@42 122
Chris@42 123
Chris@42 124 </body>
Chris@42 125 </html>