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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 d0c2a83c1364
children
rev   line source
Chris@82 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@82 2 <html>
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: Advanced Real-data DFTs</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Advanced Real-data DFTs">
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Chris@82 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@82 36 <link href="Advanced-Interface.html#Advanced-Interface" rel="up" title="Advanced Interface">
Chris@82 37 <link href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" rel="next" title="Advanced Real-to-real Transforms">
Chris@82 38 <link href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" rel="prev" title="Advanced Complex DFTs">
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Chris@82 66
Chris@82 67
Chris@82 68 </head>
Chris@82 69
Chris@82 70 <body lang="en">
Chris@82 71 <a name="Advanced-Real_002ddata-DFTs"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 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@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="Advanced-Real_002ddata-DFTs-1"></a>
Chris@82 78 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
Chris@82 79
Chris@82 80 <div class="example">
Chris@82 81 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
Chris@82 82 double *in, const int *inembed,
Chris@82 83 int istride, int idist,
Chris@82 84 fftw_complex *out, const int *onembed,
Chris@82 85 int ostride, int odist,
Chris@82 86 unsigned flags);
Chris@82 87 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
Chris@82 88 fftw_complex *in, const int *inembed,
Chris@82 89 int istride, int idist,
Chris@82 90 double *out, const int *onembed,
Chris@82 91 int ostride, int odist,
Chris@82 92 unsigned flags);
Chris@82 93 </pre></div>
Chris@82 94 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
Chris@82 95 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
Chris@82 96
Chris@82 97 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
Chris@82 98 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
Chris@82 99 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
Chris@82 100 otherwise behave the same as the basic interface.
Chris@82 101 </p>
Chris@82 102 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
Chris@82 103 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
Chris@82 104 <code>stride</code> and <code>dist</code> for the real array are in units of
Chris@82 105 <code>double</code>, and for the complex array are in units of
Chris@82 106 <code>fftw_complex</code>.
Chris@82 107 </p>
Chris@82 108 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
Chris@82 109 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@82 110 the same as <code>n</code>, but with the last dimension cut roughly in half.
Chris@82 111 For the real array, the size is assumed to be <code>n</code> if the transform
Chris@82 112 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
Chris@82 113 transform is in-place.
Chris@82 114 </p>
Chris@82 115 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
Chris@82 116 the physical size of the corresponding array, in row-major order, just
Chris@82 117 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
Chris@82 118 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
Chris@82 119 interface (e.g. the halved or padded <code>n</code>).
Chris@82 120 </p>
Chris@82 121 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
Chris@82 122 this function returns. You can safely free or reuse them.
Chris@82 123 </p>
Chris@82 124 <hr>
Chris@82 125 <div class="header">
Chris@82 126 <p>
Chris@82 127 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@82 128 </div>
Chris@82 129
Chris@82 130
Chris@82 131
Chris@82 132 </body>
Chris@82 133 </html>