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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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cannam@167 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
cannam@167 2 <html>
cannam@167 3 <!-- This manual is for FFTW
cannam@167 4 (version 3.3.8, 24 May 2018).
cannam@167 5
cannam@167 6 Copyright (C) 2003 Matteo Frigo.
cannam@167 7
cannam@167 8 Copyright (C) 2003 Massachusetts Institute of Technology.
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cannam@167 10 Permission is granted to make and distribute verbatim copies of this
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cannam@167 14 Permission is granted to copy and distribute modified versions of this
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cannam@167 16 entire resulting derived work is distributed under the terms of a
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cannam@167 24 <head>
cannam@167 25 <title>FFTW 3.3.8: Advanced Real-data DFTs</title>
cannam@167 26
cannam@167 27 <meta name="description" content="FFTW 3.3.8: Advanced Real-data DFTs">
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cannam@167 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
cannam@167 36 <link href="Advanced-Interface.html#Advanced-Interface" rel="up" title="Advanced Interface">
cannam@167 37 <link href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" rel="next" title="Advanced Real-to-real Transforms">
cannam@167 38 <link href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" rel="prev" title="Advanced Complex DFTs">
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cannam@167 68 </head>
cannam@167 69
cannam@167 70 <body lang="en">
cannam@167 71 <a name="Advanced-Real_002ddata-DFTs"></a>
cannam@167 72 <div class="header">
cannam@167 73 <p>
cannam@167 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>
cannam@167 75 </div>
cannam@167 76 <hr>
cannam@167 77 <a name="Advanced-Real_002ddata-DFTs-1"></a>
cannam@167 78 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
cannam@167 79
cannam@167 80 <div class="example">
cannam@167 81 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
cannam@167 82 double *in, const int *inembed,
cannam@167 83 int istride, int idist,
cannam@167 84 fftw_complex *out, const int *onembed,
cannam@167 85 int ostride, int odist,
cannam@167 86 unsigned flags);
cannam@167 87 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
cannam@167 88 fftw_complex *in, const int *inembed,
cannam@167 89 int istride, int idist,
cannam@167 90 double *out, const int *onembed,
cannam@167 91 int ostride, int odist,
cannam@167 92 unsigned flags);
cannam@167 93 </pre></div>
cannam@167 94 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
cannam@167 95 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
cannam@167 96
cannam@167 97 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
cannam@167 98 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
cannam@167 99 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
cannam@167 100 otherwise behave the same as the basic interface.
cannam@167 101 </p>
cannam@167 102 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
cannam@167 103 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
cannam@167 104 <code>stride</code> and <code>dist</code> for the real array are in units of
cannam@167 105 <code>double</code>, and for the complex array are in units of
cannam@167 106 <code>fftw_complex</code>.
cannam@167 107 </p>
cannam@167 108 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
cannam@167 109 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
cannam@167 110 the same as <code>n</code>, but with the last dimension cut roughly in half.
cannam@167 111 For the real array, the size is assumed to be <code>n</code> if the transform
cannam@167 112 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
cannam@167 113 transform is in-place.
cannam@167 114 </p>
cannam@167 115 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
cannam@167 116 the physical size of the corresponding array, in row-major order, just
cannam@167 117 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
cannam@167 118 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
cannam@167 119 interface (e.g. the halved or padded <code>n</code>).
cannam@167 120 </p>
cannam@167 121 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
cannam@167 122 this function returns. You can safely free or reuse them.
cannam@167 123 </p>
cannam@167 124 <hr>
cannam@167 125 <div class="header">
cannam@167 126 <p>
cannam@167 127 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>
cannam@167 128 </div>
cannam@167 129
cannam@167 130
cannam@167 131
cannam@167 132 </body>
cannam@167 133 </html>