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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
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Chris@82 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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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.
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Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: Extended and quadruple precision in Fortran</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Extended and quadruple precision in Fortran">
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Chris@82 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@82 36 <link href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" rel="up" title="Overview of Fortran interface">
Chris@82 37 <link href="Reversing-array-dimensions.html#Reversing-array-dimensions" rel="next" title="Reversing array dimensions">
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Chris@82 68 </head>
Chris@82 69
Chris@82 70 <body lang="en">
Chris@82 71 <a name="Extended-and-quadruple-precision-in-Fortran"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 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@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="Extended-and-quadruple-precision-in-Fortran-1"></a>
Chris@82 78 <h4 class="subsection">7.1.1 Extended and quadruple precision in Fortran</h4>
Chris@82 79 <a name="index-precision-7"></a>
Chris@82 80
Chris@82 81 <p>If FFTW is compiled in <code>long double</code> (extended) precision
Chris@82 82 (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>), you may be able to call the
Chris@82 83 resulting <code>fftwl_</code> routines (see <a href="Precision.html#Precision">Precision</a>) from Fortran if
Chris@82 84 your compiler supports the <code>C_LONG_DOUBLE_COMPLEX</code> type code.
Chris@82 85 </p>
Chris@82 86 <p>Because some Fortran compilers do not support
Chris@82 87 <code>C_LONG_DOUBLE_COMPLEX</code>, the <code>fftwl_</code> declarations are
Chris@82 88 segregated into a separate interface file <code>fftw3l.f03</code>, which you
Chris@82 89 should include <em>in addition</em> to <code>fftw3.f03</code> (which declares
Chris@82 90 precision-independent &lsquo;<samp>FFTW_</samp>&rsquo; constants):
Chris@82 91 </p>
Chris@82 92 <a name="index-iso_005fc_005fbinding-2"></a>
Chris@82 93 <div class="example">
Chris@82 94 <pre class="example"> use, intrinsic :: iso_c_binding
Chris@82 95 include 'fftw3.f03'
Chris@82 96 include 'fftw3l.f03'
Chris@82 97 </pre></div>
Chris@82 98
Chris@82 99 <p>We also support using the nonstandard <code>__float128</code>
Chris@82 100 quadruple-precision type provided by recent versions of <code>gcc</code> on
Chris@82 101 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>),
Chris@82 102 using the corresponding <code>real(16)</code> and <code>complex(16)</code> types
Chris@82 103 supported by <code>gfortran</code>. The quadruple-precision &lsquo;<samp>fftwq_</samp>&rsquo;
Chris@82 104 functions (see <a href="Precision.html#Precision">Precision</a>) are declared in a <code>fftw3q.f03</code>
Chris@82 105 interface file, which should be included in addition to
Chris@82 106 <code>fftw3l.f03</code>, as above. You should also link with
Chris@82 107 <code>-lfftw3q -lquadmath -lm</code> as in C.
Chris@82 108 </p>
Chris@82 109
Chris@82 110
Chris@82 111
Chris@82 112 </body>
Chris@82 113 </html>