Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.5/doc/html/Extended-and-quadruple-precision-in-Fortran.html @ 169:223a55898ab9 tip default

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add null config files
author Chris Cannam <cannam@all-day-breakfast.com>
date Mon, 02 Mar 2020 14:03:47 +0000
parents 7867fa7e1b6b
children
rev   line source
cannam@127 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
cannam@127 2 <html>
cannam@127 3 <!-- This manual is for FFTW
cannam@127 4 (version 3.3.5, 30 July 2016).
cannam@127 5
cannam@127 6 Copyright (C) 2003 Matteo Frigo.
cannam@127 7
cannam@127 8 Copyright (C) 2003 Massachusetts Institute of Technology.
cannam@127 9
cannam@127 10 Permission is granted to make and distribute verbatim copies of this
cannam@127 11 manual provided the copyright notice and this permission notice are
cannam@127 12 preserved on all copies.
cannam@127 13
cannam@127 14 Permission is granted to copy and distribute modified versions of this
cannam@127 15 manual under the conditions for verbatim copying, provided that the
cannam@127 16 entire resulting derived work is distributed under the terms of a
cannam@127 17 permission notice identical to this one.
cannam@127 18
cannam@127 19 Permission is granted to copy and distribute translations of this manual
cannam@127 20 into another language, under the above conditions for modified versions,
cannam@127 21 except that this permission notice may be stated in a translation
cannam@127 22 approved by the Free Software Foundation. -->
cannam@127 23 <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
cannam@127 24 <head>
cannam@127 25 <title>FFTW 3.3.5: Extended and quadruple precision in Fortran</title>
cannam@127 26
cannam@127 27 <meta name="description" content="FFTW 3.3.5: Extended and quadruple precision in Fortran">
cannam@127 28 <meta name="keywords" content="FFTW 3.3.5: Extended and quadruple precision in Fortran">
cannam@127 29 <meta name="resource-type" content="document">
cannam@127 30 <meta name="distribution" content="global">
cannam@127 31 <meta name="Generator" content="makeinfo">
cannam@127 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
cannam@127 33 <link href="index.html#Top" rel="start" title="Top">
cannam@127 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
cannam@127 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
cannam@127 36 <link href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" rel="up" title="Overview of Fortran interface">
cannam@127 37 <link href="Reversing-array-dimensions.html#Reversing-array-dimensions" rel="next" title="Reversing array dimensions">
cannam@127 38 <link href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" rel="prev" title="Overview of Fortran interface">
cannam@127 39 <style type="text/css">
cannam@127 40 <!--
cannam@127 41 a.summary-letter {text-decoration: none}
cannam@127 42 blockquote.smallquotation {font-size: smaller}
cannam@127 43 div.display {margin-left: 3.2em}
cannam@127 44 div.example {margin-left: 3.2em}
cannam@127 45 div.indentedblock {margin-left: 3.2em}
cannam@127 46 div.lisp {margin-left: 3.2em}
cannam@127 47 div.smalldisplay {margin-left: 3.2em}
cannam@127 48 div.smallexample {margin-left: 3.2em}
cannam@127 49 div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
cannam@127 50 div.smalllisp {margin-left: 3.2em}
cannam@127 51 kbd {font-style:oblique}
cannam@127 52 pre.display {font-family: inherit}
cannam@127 53 pre.format {font-family: inherit}
cannam@127 54 pre.menu-comment {font-family: serif}
cannam@127 55 pre.menu-preformatted {font-family: serif}
cannam@127 56 pre.smalldisplay {font-family: inherit; font-size: smaller}
cannam@127 57 pre.smallexample {font-size: smaller}
cannam@127 58 pre.smallformat {font-family: inherit; font-size: smaller}
cannam@127 59 pre.smalllisp {font-size: smaller}
cannam@127 60 span.nocodebreak {white-space:nowrap}
cannam@127 61 span.nolinebreak {white-space:nowrap}
cannam@127 62 span.roman {font-family:serif; font-weight:normal}
cannam@127 63 span.sansserif {font-family:sans-serif; font-weight:normal}
cannam@127 64 ul.no-bullet {list-style: none}
cannam@127 65 -->
cannam@127 66 </style>
cannam@127 67
cannam@127 68
cannam@127 69 </head>
cannam@127 70
cannam@127 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
cannam@127 72 <a name="Extended-and-quadruple-precision-in-Fortran"></a>
cannam@127 73 <div class="header">
cannam@127 74 <p>
cannam@127 75 Previous: <a href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" accesskey="p" rel="prev">Overview of Fortran interface</a>, Up: <a href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" accesskey="u" rel="up">Overview of Fortran interface</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@127 76 </div>
cannam@127 77 <hr>
cannam@127 78 <a name="Extended-and-quadruple-precision-in-Fortran-1"></a>
cannam@127 79 <h4 class="subsection">7.1.1 Extended and quadruple precision in Fortran</h4>
cannam@127 80 <a name="index-precision-7"></a>
cannam@127 81
cannam@127 82 <p>If FFTW is compiled in <code>long double</code> (extended) precision
cannam@127 83 (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>), you may be able to call the
cannam@127 84 resulting <code>fftwl_</code> routines (see <a href="Precision.html#Precision">Precision</a>) from Fortran if
cannam@127 85 your compiler supports the <code>C_LONG_DOUBLE_COMPLEX</code> type code.
cannam@127 86 </p>
cannam@127 87 <p>Because some Fortran compilers do not support
cannam@127 88 <code>C_LONG_DOUBLE_COMPLEX</code>, the <code>fftwl_</code> declarations are
cannam@127 89 segregated into a separate interface file <code>fftw3l.f03</code>, which you
cannam@127 90 should include <em>in addition</em> to <code>fftw3.f03</code> (which declares
cannam@127 91 precision-independent &lsquo;<samp>FFTW_</samp>&rsquo; constants):
cannam@127 92 </p>
cannam@127 93 <a name="index-iso_005fc_005fbinding-2"></a>
cannam@127 94 <div class="example">
cannam@127 95 <pre class="example"> use, intrinsic :: iso_c_binding
cannam@127 96 include 'fftw3.f03'
cannam@127 97 include 'fftw3l.f03'
cannam@127 98 </pre></div>
cannam@127 99
cannam@127 100 <p>We also support using the nonstandard <code>__float128</code>
cannam@127 101 quadruple-precision type provided by recent versions of <code>gcc</code> on
cannam@127 102 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>),
cannam@127 103 using the corresponding <code>real(16)</code> and <code>complex(16)</code> types
cannam@127 104 supported by <code>gfortran</code>. The quadruple-precision &lsquo;<samp>fftwq_</samp>&rsquo;
cannam@127 105 functions (see <a href="Precision.html#Precision">Precision</a>) are declared in a <code>fftw3q.f03</code>
cannam@127 106 interface file, which should be included in addition to
cannam@127 107 <code>fftw3l.f03</code>, as above. You should also link with
cannam@127 108 <code>-lfftw3q -lquadmath -lm</code> as in C.
cannam@127 109 </p>
cannam@127 110
cannam@127 111
cannam@127 112
cannam@127 113 </body>
cannam@127 114 </html>