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Tidy up for ROLI
author Geogaddi\David <d.m.ronan@qmul.ac.uk>
date Tue, 17 May 2016 18:50:19 +0100
parents 636c989477e7
children
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1 <html lang="en">
2 <head>
3 <title>Precision - FFTW 3.2.1</title>
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11 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
12 <!--
13 This manual is for FFTW
14 (version 3.2.1, 5 February 2009).
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16 Copyright (C) 2003 Matteo Frigo.
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18 Copyright (C) 2003 Massachusetts Institute of Technology.
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27 terms of a permission notice identical to this one.
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48 <div class="node">
49 <p>
50 <a name="Precision"></a>
51 Next:&nbsp;<a rel="next" accesskey="n" href="Memory-Allocation.html#Memory-Allocation">Memory Allocation</a>,
52 Previous:&nbsp;<a rel="previous" accesskey="p" href="Complex-numbers.html#Complex-numbers">Complex numbers</a>,
53 Up:&nbsp;<a rel="up" accesskey="u" href="Data-Types-and-Files.html#Data-Types-and-Files">Data Types and Files</a>
54 <hr>
55 </div>
56
57 <h4 class="subsection">4.1.2 Precision</h4>
58
59 <p><a name="index-precision-140"></a>
60 You can install single and long-double precision versions of FFTW,
61 which replace <code>double</code> with <code>float</code> and <code>long double</code>,
62 respectively (see <a href="Installation-and-Customization.html#Installation-and-Customization">Installation and Customization</a>). To use these
63 interfaces, you:
64
65 <ul>
66 <li>Link to the single/long-double libraries; on Unix, <code>-lfftw3f</code> or
67 <code>-lfftw3l</code> instead of (or in addition to) <code>-lfftw3</code>. (You
68 can link to the different-precision libraries simultaneously.)
69
70 <li>Include the <em>same</em> <code>&lt;fftw3.h&gt;</code> header file.
71
72 <li>Replace all lowercase instances of `<samp><span class="samp">fftw_</span></samp>' with `<samp><span class="samp">fftwf_</span></samp>' or
73 <code>fftwl_</code> for single or long-double precision, respectively.
74 (<code>fftw_complex</code> becomes <code>fftwf_complex</code>, <code>fftw_execute</code>
75 becomes <code>fftwf_execute</code>, etcetera.)
76
77 <li>Uppercase names, i.e. names beginning with `<samp><span class="samp">FFTW_</span></samp>', remain the
78 same.
79
80 <li>Replace <code>double</code> with <code>float</code> or <code>long double</code> for
81 subroutine parameters.
82
83 </ul>
84
85 <p>Depending upon your compiler and/or hardware, <code>long double</code> may not
86 be any more precise than <code>double</code> (or may not be supported at all,
87 although it is standard in C99).
88 <a name="index-C99-141"></a>
89 <!-- =========> -->
90
91 </body></html>
92