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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 2cd0e3b3e1fd
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">
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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.
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Chris@42 8 Copyright (C) 2003 Massachusetts Institute of Technology.
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Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Extended and quadruple precision in Fortran</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Extended and quadruple precision in Fortran">
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Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" rel="up" title="Overview of Fortran interface">
Chris@42 37 <link href="Reversing-array-dimensions.html#Reversing-array-dimensions" rel="next" title="Reversing array dimensions">
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Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Extended-and-quadruple-precision-in-Fortran"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 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>
Chris@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Extended-and-quadruple-precision-in-Fortran-1"></a>
Chris@42 79 <h4 class="subsection">7.1.1 Extended and quadruple precision in Fortran</h4>
Chris@42 80 <a name="index-precision-7"></a>
Chris@42 81
Chris@42 82 <p>If FFTW is compiled in <code>long double</code> (extended) precision
Chris@42 83 (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>), you may be able to call the
Chris@42 84 resulting <code>fftwl_</code> routines (see <a href="Precision.html#Precision">Precision</a>) from Fortran if
Chris@42 85 your compiler supports the <code>C_LONG_DOUBLE_COMPLEX</code> type code.
Chris@42 86 </p>
Chris@42 87 <p>Because some Fortran compilers do not support
Chris@42 88 <code>C_LONG_DOUBLE_COMPLEX</code>, the <code>fftwl_</code> declarations are
Chris@42 89 segregated into a separate interface file <code>fftw3l.f03</code>, which you
Chris@42 90 should include <em>in addition</em> to <code>fftw3.f03</code> (which declares
Chris@42 91 precision-independent &lsquo;<samp>FFTW_</samp>&rsquo; constants):
Chris@42 92 </p>
Chris@42 93 <a name="index-iso_005fc_005fbinding-2"></a>
Chris@42 94 <div class="example">
Chris@42 95 <pre class="example"> use, intrinsic :: iso_c_binding
Chris@42 96 include 'fftw3.f03'
Chris@42 97 include 'fftw3l.f03'
Chris@42 98 </pre></div>
Chris@42 99
Chris@42 100 <p>We also support using the nonstandard <code>__float128</code>
Chris@42 101 quadruple-precision type provided by recent versions of <code>gcc</code> on
Chris@42 102 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>),
Chris@42 103 using the corresponding <code>real(16)</code> and <code>complex(16)</code> types
Chris@42 104 supported by <code>gfortran</code>. The quadruple-precision &lsquo;<samp>fftwq_</samp>&rsquo;
Chris@42 105 functions (see <a href="Precision.html#Precision">Precision</a>) are declared in a <code>fftw3q.f03</code>
Chris@42 106 interface file, which should be included in addition to
Chris@42 107 <code>fftw3l.f03</code>, as above. You should also link with
Chris@42 108 <code>-lfftw3q -lquadmath -lm</code> as in C.
Chris@42 109 </p>
Chris@42 110
Chris@42 111
Chris@42 112
Chris@42 113 </body>
Chris@42 114 </html>