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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.
Chris@82 9
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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>