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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 37bf6b4a2645
children
rev   line source
Chris@10 1 <html lang="en">
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Chris@10 3 <title>Precision - FFTW 3.3.3</title>
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Chris@10 12 <!--
Chris@10 13 This manual is for FFTW
Chris@10 14 (version 3.3.3, 25 November 2012).
Chris@10 15
Chris@10 16 Copyright (C) 2003 Matteo Frigo.
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Chris@10 18 Copyright (C) 2003 Massachusetts Institute of Technology.
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Chris@10 26 that the entire resulting derived work is distributed under the
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Chris@10 29 Permission is granted to copy and distribute translations of this
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Chris@10 46 </head>
Chris@10 47 <body>
Chris@10 48 <div class="node">
Chris@10 49 <a name="Precision"></a>
Chris@10 50 <p>
Chris@10 51 Next:&nbsp;<a rel="next" accesskey="n" href="Memory-Allocation.html#Memory-Allocation">Memory Allocation</a>,
Chris@10 52 Previous:&nbsp;<a rel="previous" accesskey="p" href="Complex-numbers.html#Complex-numbers">Complex numbers</a>,
Chris@10 53 Up:&nbsp;<a rel="up" accesskey="u" href="Data-Types-and-Files.html#Data-Types-and-Files">Data Types and Files</a>
Chris@10 54 <hr>
Chris@10 55 </div>
Chris@10 56
Chris@10 57 <h4 class="subsection">4.1.2 Precision</h4>
Chris@10 58
Chris@10 59 <p><a name="index-precision-143"></a>
Chris@10 60 You can install single and long-double precision versions of FFTW,
Chris@10 61 which replace <code>double</code> with <code>float</code> and <code>long double</code>,
Chris@10 62 respectively (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>). To use these
Chris@10 63 interfaces, you:
Chris@10 64
Chris@10 65 <ul>
Chris@10 66 <li>Link to the single/long-double libraries; on Unix, <code>-lfftw3f</code> or
Chris@10 67 <code>-lfftw3l</code> instead of (or in addition to) <code>-lfftw3</code>. (You
Chris@10 68 can link to the different-precision libraries simultaneously.)
Chris@10 69
Chris@10 70 <li>Include the <em>same</em> <code>&lt;fftw3.h&gt;</code> header file.
Chris@10 71
Chris@10 72 <li>Replace all lowercase instances of &lsquo;<samp><span class="samp">fftw_</span></samp>&rsquo; with &lsquo;<samp><span class="samp">fftwf_</span></samp>&rsquo; or
Chris@10 73 &lsquo;<samp><span class="samp">fftwl_</span></samp>&rsquo; for single or long-double precision, respectively.
Chris@10 74 (<code>fftw_complex</code> becomes <code>fftwf_complex</code>, <code>fftw_execute</code>
Chris@10 75 becomes <code>fftwf_execute</code>, etcetera.)
Chris@10 76
Chris@10 77 <li>Uppercase names, i.e. names beginning with &lsquo;<samp><span class="samp">FFTW_</span></samp>&rsquo;, remain the
Chris@10 78 same.
Chris@10 79
Chris@10 80 <li>Replace <code>double</code> with <code>float</code> or <code>long double</code> for
Chris@10 81 subroutine parameters.
Chris@10 82
Chris@10 83 </ul>
Chris@10 84
Chris@10 85 <p>Depending upon your compiler and/or hardware, <code>long double</code> may not
Chris@10 86 be any more precise than <code>double</code> (or may not be supported at all,
Chris@10 87 although it is standard in C99).
Chris@10 88 <a name="index-C99-144"></a>
Chris@10 89
Chris@10 90 <p>We also support using the nonstandard <code>__float128</code>
Chris@10 91 quadruple-precision type provided by recent versions of <code>gcc</code> on
Chris@10 92 32- and 64-bit x86 hardware (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>).
Chris@10 93 To use this type, link with <code>-lfftw3q -lquadmath -lm</code> (the
Chris@10 94 <code>libquadmath</code> library provided by <code>gcc</code> is needed for
Chris@10 95 quadruple-precision trigonometric functions) and use &lsquo;<samp><span class="samp">fftwq_</span></samp>&rsquo;
Chris@10 96 identifiers.
Chris@10 97
Chris@10 98 <!-- =========> -->
Chris@10 99 </body></html>
Chris@10 100