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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
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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.
Chris@82 9
Chris@82 10 Permission is granted to make and distribute verbatim copies of this
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Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: Guru Real-data DFTs</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Guru Real-data DFTs">
Chris@82 28 <meta name="keywords" content="FFTW 3.3.8: Guru 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="Guru-Interface.html#Guru-Interface" rel="up" title="Guru Interface">
Chris@82 37 <link href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" rel="next" title="Guru Real-to-real Transforms">
Chris@82 38 <link href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" rel="prev" title="Guru 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="Guru-Real_002ddata-DFTs"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 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>
Chris@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="Guru-Real_002ddata-DFTs-1"></a>
Chris@82 78 <h4 class="subsection">4.5.4 Guru Real-data DFTs</h4>
Chris@82 79
Chris@82 80 <div class="example">
Chris@82 81 <pre class="example">fftw_plan fftw_plan_guru_dft_r2c(
Chris@82 82 int rank, const fftw_iodim *dims,
Chris@82 83 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@82 84 double *in, fftw_complex *out,
Chris@82 85 unsigned flags);
Chris@82 86
Chris@82 87 fftw_plan fftw_plan_guru_split_dft_r2c(
Chris@82 88 int rank, const fftw_iodim *dims,
Chris@82 89 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@82 90 double *in, double *ro, double *io,
Chris@82 91 unsigned flags);
Chris@82 92
Chris@82 93 fftw_plan fftw_plan_guru_dft_c2r(
Chris@82 94 int rank, const fftw_iodim *dims,
Chris@82 95 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@82 96 fftw_complex *in, double *out,
Chris@82 97 unsigned flags);
Chris@82 98
Chris@82 99 fftw_plan fftw_plan_guru_split_dft_c2r(
Chris@82 100 int rank, const fftw_iodim *dims,
Chris@82 101 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@82 102 double *ri, double *ii, double *out,
Chris@82 103 unsigned flags);
Chris@82 104 </pre></div>
Chris@82 105 <a name="index-fftw_005fplan_005fguru_005fdft_005fr2c"></a>
Chris@82 106 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fr2c"></a>
Chris@82 107 <a name="index-fftw_005fplan_005fguru_005fdft_005fc2r"></a>
Chris@82 108 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fc2r"></a>
Chris@82 109
Chris@82 110 <p>Plan a real-input (r2c) or real-output (c2r), multi-dimensional DFT with
Chris@82 111 transform dimensions given by (<code>rank</code>, <code>dims</code>) over a
Chris@82 112 multi-dimensional vector (loop) of dimensions (<code>howmany_rank</code>,
Chris@82 113 <code>howmany_dims</code>). <code>dims</code> and <code>howmany_dims</code> should point
Chris@82 114 to <code>fftw_iodim</code> arrays of length <code>rank</code> and
Chris@82 115 <code>howmany_rank</code>, respectively. As for the basic and advanced
Chris@82 116 interfaces, an r2c transform is <code>FFTW_FORWARD</code> and a c2r transform
Chris@82 117 is <code>FFTW_BACKWARD</code>.
Chris@82 118 </p>
Chris@82 119 <p>The <em>last</em> dimension of <code>dims</code> is interpreted specially:
Chris@82 120 that dimension of the real array has size <code>dims[rank-1].n</code>, but
Chris@82 121 that dimension of the complex array has size <code>dims[rank-1].n/2+1</code>
Chris@82 122 (division rounded down). The strides, on the other hand, are taken to
Chris@82 123 be exactly as specified. It is up to the user to specify the strides
Chris@82 124 appropriately for the peculiar dimensions of the data, and we do not
Chris@82 125 guarantee that the planner will succeed (return non-<code>NULL</code>) for
Chris@82 126 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,
Chris@82 127 for an in-place transform, each individual dimension should be able to
Chris@82 128 operate in place.)
Chris@82 129 <a name="index-in_002dplace-6"></a>
Chris@82 130 </p>
Chris@82 131
Chris@82 132 <p><code>in</code> and <code>out</code> point to the input and output arrays for r2c
Chris@82 133 and c2r transforms, respectively. For split arrays, <code>ri</code> and
Chris@82 134 <code>ii</code> point to the real and imaginary input arrays for a c2r
Chris@82 135 transform, and <code>ro</code> and <code>io</code> point to the real and imaginary
Chris@82 136 output arrays for an r2c transform. <code>in</code> and <code>ro</code> or
Chris@82 137 <code>ri</code> and <code>out</code> may be the same, indicating an in-place
Chris@82 138 transform. (In-place transforms where <code>in</code> and <code>io</code> or
Chris@82 139 <code>ii</code> and <code>out</code> are the same are not currently supported.)
Chris@82 140 </p>
Chris@82 141 <a name="index-flags-6"></a>
Chris@82 142 <p><code>flags</code> is a bitwise OR (&lsquo;<samp>|</samp>&rsquo;) of zero or more planner flags,
Chris@82 143 as defined in <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>.
Chris@82 144 </p>
Chris@82 145 <p>In-place transforms of rank greater than 1 are currently only
Chris@82 146 supported for interleaved arrays. For split arrays, the planner will
Chris@82 147 return <code>NULL</code>.
Chris@82 148 <a name="index-in_002dplace-7"></a>
Chris@82 149 </p>
Chris@82 150 <hr>
Chris@82 151 <div class="header">
Chris@82 152 <p>
Chris@82 153 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>
Chris@82 154 </div>
Chris@82 155
Chris@82 156
Chris@82 157
Chris@82 158 </body>
Chris@82 159 </html>