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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Nov 2019 14:52:55 +0000
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3 <!-- This manual is for FFTW
4 (version 3.3.8, 24 May 2018).
5
6 Copyright (C) 2003 Matteo Frigo.
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8 Copyright (C) 2003 Massachusetts Institute of Technology.
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24 <head>
25 <title>FFTW 3.3.8: Extended and quadruple precision in Fortran</title>
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35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
36 <link href="Overview-of-Fortran-interface.html#Overview-of-Fortran-interface" rel="up" title="Overview of Fortran interface">
37 <link href="Reversing-array-dimensions.html#Reversing-array-dimensions" rel="next" title="Reversing array dimensions">
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71 <a name="Extended-and-quadruple-precision-in-Fortran"></a>
72 <div class="header">
73 <p>
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>
75 </div>
76 <hr>
77 <a name="Extended-and-quadruple-precision-in-Fortran-1"></a>
78 <h4 class="subsection">7.1.1 Extended and quadruple precision in Fortran</h4>
79 <a name="index-precision-7"></a>
80
81 <p>If FFTW is compiled in <code>long double</code> (extended) precision
82 (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>), you may be able to call the
83 resulting <code>fftwl_</code> routines (see <a href="Precision.html#Precision">Precision</a>) from Fortran if
84 your compiler supports the <code>C_LONG_DOUBLE_COMPLEX</code> type code.
85 </p>
86 <p>Because some Fortran compilers do not support
87 <code>C_LONG_DOUBLE_COMPLEX</code>, the <code>fftwl_</code> declarations are
88 segregated into a separate interface file <code>fftw3l.f03</code>, which you
89 should include <em>in addition</em> to <code>fftw3.f03</code> (which declares
90 precision-independent &lsquo;<samp>FFTW_</samp>&rsquo; constants):
91 </p>
92 <a name="index-iso_005fc_005fbinding-2"></a>
93 <div class="example">
94 <pre class="example"> use, intrinsic :: iso_c_binding
95 include 'fftw3.f03'
96 include 'fftw3l.f03'
97 </pre></div>
98
99 <p>We also support using the nonstandard <code>__float128</code>
100 quadruple-precision type provided by recent versions of <code>gcc</code> on
101 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>),
102 using the corresponding <code>real(16)</code> and <code>complex(16)</code> types
103 supported by <code>gfortran</code>. The quadruple-precision &lsquo;<samp>fftwq_</samp>&rsquo;
104 functions (see <a href="Precision.html#Precision">Precision</a>) are declared in a <code>fftw3q.f03</code>
105 interface file, which should be included in addition to
106 <code>fftw3l.f03</code>, as above. You should also link with
107 <code>-lfftw3q -lquadmath -lm</code> as in C.
108 </p>
109
110
111
112 </body>
113 </html>