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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">
Chris@42 2 <html>
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: Advanced Real-data DFTs</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Advanced Real-data DFTs">
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Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Advanced-Interface.html#Advanced-Interface" rel="up" title="Advanced Interface">
Chris@42 37 <link href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" rel="next" title="Advanced Real-to-real Transforms">
Chris@42 38 <link href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" rel="prev" title="Advanced Complex DFTs">
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Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Advanced-Real_002ddata-DFTs"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Next: <a href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Advanced Real-to-real Transforms</a>, Previous: <a href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" accesskey="p" rel="prev">Advanced Complex DFTs</a>, Up: <a href="Advanced-Interface.html#Advanced-Interface" accesskey="u" rel="up">Advanced 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="Advanced-Real_002ddata-DFTs-1"></a>
Chris@42 79 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
Chris@42 80
Chris@42 81 <div class="example">
Chris@42 82 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
Chris@42 83 double *in, const int *inembed,
Chris@42 84 int istride, int idist,
Chris@42 85 fftw_complex *out, const int *onembed,
Chris@42 86 int ostride, int odist,
Chris@42 87 unsigned flags);
Chris@42 88 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
Chris@42 89 fftw_complex *in, const int *inembed,
Chris@42 90 int istride, int idist,
Chris@42 91 double *out, const int *onembed,
Chris@42 92 int ostride, int odist,
Chris@42 93 unsigned flags);
Chris@42 94 </pre></div>
Chris@42 95 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
Chris@42 96 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
Chris@42 97
Chris@42 98 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
Chris@42 99 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
Chris@42 100 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
Chris@42 101 otherwise behave the same as the basic interface.
Chris@42 102 </p>
Chris@42 103 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
Chris@42 104 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
Chris@42 105 <code>stride</code> and <code>dist</code> for the real array are in units of
Chris@42 106 <code>double</code>, and for the complex array are in units of
Chris@42 107 <code>fftw_complex</code>.
Chris@42 108 </p>
Chris@42 109 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
Chris@42 110 it would be in the basic interface, as described in <a href="Real_002ddata-DFT-Array-Format.html#Real_002ddata-DFT-Array-Format">Real-data DFT Array Format</a>. That is, for the complex array the size is assumed to be
Chris@42 111 the same as <code>n</code>, but with the last dimension cut roughly in half.
Chris@42 112 For the real array, the size is assumed to be <code>n</code> if the transform
Chris@42 113 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
Chris@42 114 transform is in-place.
Chris@42 115 </p>
Chris@42 116 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
Chris@42 117 the physical size of the corresponding array, in row-major order, just
Chris@42 118 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
Chris@42 119 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
Chris@42 120 interface (e.g. the halved or padded <code>n</code>).
Chris@42 121 </p>
Chris@42 122 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
Chris@42 123 this function returns. You can safely free or reuse them.
Chris@42 124 </p>
Chris@42 125 <hr>
Chris@42 126 <div class="header">
Chris@42 127 <p>
Chris@42 128 Next: <a href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Advanced Real-to-real Transforms</a>, Previous: <a href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" accesskey="p" rel="prev">Advanced Complex DFTs</a>, Up: <a href="Advanced-Interface.html#Advanced-Interface" accesskey="u" rel="up">Advanced 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@42 129 </div>
Chris@42 130
Chris@42 131
Chris@42 132
Chris@42 133 </body>
Chris@42 134 </html>