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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: Guru Real-data DFTs</title>
cannam@167 26
cannam@167 27 <meta name="description" content="FFTW 3.3.8: Guru 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="Guru-Interface.html#Guru-Interface" rel="up" title="Guru Interface">
cannam@167 37 <link href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" rel="next" title="Guru Real-to-real Transforms">
cannam@167 38 <link href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" rel="prev" title="Guru Complex DFTs">
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cannam@167 68 </head>
cannam@167 69
cannam@167 70 <body lang="en">
cannam@167 71 <a name="Guru-Real_002ddata-DFTs"></a>
cannam@167 72 <div class="header">
cannam@167 73 <p>
cannam@167 74 Next: <a href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Guru Real-to-real Transforms</a>, Previous: <a href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" accesskey="p" rel="prev">Guru Complex DFTs</a>, Up: <a href="Guru-Interface.html#Guru-Interface" accesskey="u" rel="up">Guru 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="Guru-Real_002ddata-DFTs-1"></a>
cannam@167 78 <h4 class="subsection">4.5.4 Guru Real-data DFTs</h4>
cannam@167 79
cannam@167 80 <div class="example">
cannam@167 81 <pre class="example">fftw_plan fftw_plan_guru_dft_r2c(
cannam@167 82 int rank, const fftw_iodim *dims,
cannam@167 83 int howmany_rank, const fftw_iodim *howmany_dims,
cannam@167 84 double *in, fftw_complex *out,
cannam@167 85 unsigned flags);
cannam@167 86
cannam@167 87 fftw_plan fftw_plan_guru_split_dft_r2c(
cannam@167 88 int rank, const fftw_iodim *dims,
cannam@167 89 int howmany_rank, const fftw_iodim *howmany_dims,
cannam@167 90 double *in, double *ro, double *io,
cannam@167 91 unsigned flags);
cannam@167 92
cannam@167 93 fftw_plan fftw_plan_guru_dft_c2r(
cannam@167 94 int rank, const fftw_iodim *dims,
cannam@167 95 int howmany_rank, const fftw_iodim *howmany_dims,
cannam@167 96 fftw_complex *in, double *out,
cannam@167 97 unsigned flags);
cannam@167 98
cannam@167 99 fftw_plan fftw_plan_guru_split_dft_c2r(
cannam@167 100 int rank, const fftw_iodim *dims,
cannam@167 101 int howmany_rank, const fftw_iodim *howmany_dims,
cannam@167 102 double *ri, double *ii, double *out,
cannam@167 103 unsigned flags);
cannam@167 104 </pre></div>
cannam@167 105 <a name="index-fftw_005fplan_005fguru_005fdft_005fr2c"></a>
cannam@167 106 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fr2c"></a>
cannam@167 107 <a name="index-fftw_005fplan_005fguru_005fdft_005fc2r"></a>
cannam@167 108 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fc2r"></a>
cannam@167 109
cannam@167 110 <p>Plan a real-input (r2c) or real-output (c2r), multi-dimensional DFT with
cannam@167 111 transform dimensions given by (<code>rank</code>, <code>dims</code>) over a
cannam@167 112 multi-dimensional vector (loop) of dimensions (<code>howmany_rank</code>,
cannam@167 113 <code>howmany_dims</code>). <code>dims</code> and <code>howmany_dims</code> should point
cannam@167 114 to <code>fftw_iodim</code> arrays of length <code>rank</code> and
cannam@167 115 <code>howmany_rank</code>, respectively. As for the basic and advanced
cannam@167 116 interfaces, an r2c transform is <code>FFTW_FORWARD</code> and a c2r transform
cannam@167 117 is <code>FFTW_BACKWARD</code>.
cannam@167 118 </p>
cannam@167 119 <p>The <em>last</em> dimension of <code>dims</code> is interpreted specially:
cannam@167 120 that dimension of the real array has size <code>dims[rank-1].n</code>, but
cannam@167 121 that dimension of the complex array has size <code>dims[rank-1].n/2+1</code>
cannam@167 122 (division rounded down). The strides, on the other hand, are taken to
cannam@167 123 be exactly as specified. It is up to the user to specify the strides
cannam@167 124 appropriately for the peculiar dimensions of the data, and we do not
cannam@167 125 guarantee that the planner will succeed (return non-<code>NULL</code>) for
cannam@167 126 any dimensions other than those described in <a href="Real_002ddata-DFT-Array-Format.html#Real_002ddata-DFT-Array-Format">Real-data DFT Array Format</a> and generalized in <a href="Advanced-Real_002ddata-DFTs.html#Advanced-Real_002ddata-DFTs">Advanced Real-data DFTs</a>. (That is,
cannam@167 127 for an in-place transform, each individual dimension should be able to
cannam@167 128 operate in place.)
cannam@167 129 <a name="index-in_002dplace-6"></a>
cannam@167 130 </p>
cannam@167 131
cannam@167 132 <p><code>in</code> and <code>out</code> point to the input and output arrays for r2c
cannam@167 133 and c2r transforms, respectively. For split arrays, <code>ri</code> and
cannam@167 134 <code>ii</code> point to the real and imaginary input arrays for a c2r
cannam@167 135 transform, and <code>ro</code> and <code>io</code> point to the real and imaginary
cannam@167 136 output arrays for an r2c transform. <code>in</code> and <code>ro</code> or
cannam@167 137 <code>ri</code> and <code>out</code> may be the same, indicating an in-place
cannam@167 138 transform. (In-place transforms where <code>in</code> and <code>io</code> or
cannam@167 139 <code>ii</code> and <code>out</code> are the same are not currently supported.)
cannam@167 140 </p>
cannam@167 141 <a name="index-flags-6"></a>
cannam@167 142 <p><code>flags</code> is a bitwise OR (&lsquo;<samp>|</samp>&rsquo;) of zero or more planner flags,
cannam@167 143 as defined in <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>.
cannam@167 144 </p>
cannam@167 145 <p>In-place transforms of rank greater than 1 are currently only
cannam@167 146 supported for interleaved arrays. For split arrays, the planner will
cannam@167 147 return <code>NULL</code>.
cannam@167 148 <a name="index-in_002dplace-7"></a>
cannam@167 149 </p>
cannam@167 150 <hr>
cannam@167 151 <div class="header">
cannam@167 152 <p>
cannam@167 153 Next: <a href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Guru Real-to-real Transforms</a>, Previous: <a href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" accesskey="p" rel="prev">Guru Complex DFTs</a>, Up: <a href="Guru-Interface.html#Guru-Interface" accesskey="u" rel="up">Guru 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@167 154 </div>
cannam@167 155
cannam@167 156
cannam@167 157
cannam@167 158 </body>
cannam@167 159 </html>