Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.5/doc/html/Guru-Real_002ddata-DFTs.html @ 83:ae30d91d2ffe

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
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 2cd0e3b3e1fd
children
rev   line source
Chris@42 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@42 2 <html>
Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
Chris@42 5
Chris@42 6 Copyright (C) 2003 Matteo Frigo.
Chris@42 7
Chris@42 8 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@42 9
Chris@42 10 Permission is granted to make and distribute verbatim copies of this
Chris@42 11 manual provided the copyright notice and this permission notice are
Chris@42 12 preserved on all copies.
Chris@42 13
Chris@42 14 Permission is granted to copy and distribute modified versions of this
Chris@42 15 manual under the conditions for verbatim copying, provided that the
Chris@42 16 entire resulting derived work is distributed under the terms of a
Chris@42 17 permission notice identical to this one.
Chris@42 18
Chris@42 19 Permission is granted to copy and distribute translations of this manual
Chris@42 20 into another language, under the above conditions for modified versions,
Chris@42 21 except that this permission notice may be stated in a translation
Chris@42 22 approved by the Free Software Foundation. -->
Chris@42 23 <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Guru Real-data DFTs</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Guru Real-data DFTs">
Chris@42 28 <meta name="keywords" content="FFTW 3.3.5: Guru Real-data DFTs">
Chris@42 29 <meta name="resource-type" content="document">
Chris@42 30 <meta name="distribution" content="global">
Chris@42 31 <meta name="Generator" content="makeinfo">
Chris@42 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Chris@42 33 <link href="index.html#Top" rel="start" title="Top">
Chris@42 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Guru-Interface.html#Guru-Interface" rel="up" title="Guru Interface">
Chris@42 37 <link href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" rel="next" title="Guru Real-to-real Transforms">
Chris@42 38 <link href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" rel="prev" title="Guru Complex DFTs">
Chris@42 39 <style type="text/css">
Chris@42 40 <!--
Chris@42 41 a.summary-letter {text-decoration: none}
Chris@42 42 blockquote.smallquotation {font-size: smaller}
Chris@42 43 div.display {margin-left: 3.2em}
Chris@42 44 div.example {margin-left: 3.2em}
Chris@42 45 div.indentedblock {margin-left: 3.2em}
Chris@42 46 div.lisp {margin-left: 3.2em}
Chris@42 47 div.smalldisplay {margin-left: 3.2em}
Chris@42 48 div.smallexample {margin-left: 3.2em}
Chris@42 49 div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
Chris@42 50 div.smalllisp {margin-left: 3.2em}
Chris@42 51 kbd {font-style:oblique}
Chris@42 52 pre.display {font-family: inherit}
Chris@42 53 pre.format {font-family: inherit}
Chris@42 54 pre.menu-comment {font-family: serif}
Chris@42 55 pre.menu-preformatted {font-family: serif}
Chris@42 56 pre.smalldisplay {font-family: inherit; font-size: smaller}
Chris@42 57 pre.smallexample {font-size: smaller}
Chris@42 58 pre.smallformat {font-family: inherit; font-size: smaller}
Chris@42 59 pre.smalllisp {font-size: smaller}
Chris@42 60 span.nocodebreak {white-space:nowrap}
Chris@42 61 span.nolinebreak {white-space:nowrap}
Chris@42 62 span.roman {font-family:serif; font-weight:normal}
Chris@42 63 span.sansserif {font-family:sans-serif; font-weight:normal}
Chris@42 64 ul.no-bullet {list-style: none}
Chris@42 65 -->
Chris@42 66 </style>
Chris@42 67
Chris@42 68
Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Guru-Real_002ddata-DFTs"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 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@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Guru-Real_002ddata-DFTs-1"></a>
Chris@42 79 <h4 class="subsection">4.5.4 Guru Real-data DFTs</h4>
Chris@42 80
Chris@42 81 <div class="example">
Chris@42 82 <pre class="example">fftw_plan fftw_plan_guru_dft_r2c(
Chris@42 83 int rank, const fftw_iodim *dims,
Chris@42 84 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@42 85 double *in, fftw_complex *out,
Chris@42 86 unsigned flags);
Chris@42 87
Chris@42 88 fftw_plan fftw_plan_guru_split_dft_r2c(
Chris@42 89 int rank, const fftw_iodim *dims,
Chris@42 90 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@42 91 double *in, double *ro, double *io,
Chris@42 92 unsigned flags);
Chris@42 93
Chris@42 94 fftw_plan fftw_plan_guru_dft_c2r(
Chris@42 95 int rank, const fftw_iodim *dims,
Chris@42 96 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@42 97 fftw_complex *in, double *out,
Chris@42 98 unsigned flags);
Chris@42 99
Chris@42 100 fftw_plan fftw_plan_guru_split_dft_c2r(
Chris@42 101 int rank, const fftw_iodim *dims,
Chris@42 102 int howmany_rank, const fftw_iodim *howmany_dims,
Chris@42 103 double *ri, double *ii, double *out,
Chris@42 104 unsigned flags);
Chris@42 105 </pre></div>
Chris@42 106 <a name="index-fftw_005fplan_005fguru_005fdft_005fr2c"></a>
Chris@42 107 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fr2c"></a>
Chris@42 108 <a name="index-fftw_005fplan_005fguru_005fdft_005fc2r"></a>
Chris@42 109 <a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fc2r"></a>
Chris@42 110
Chris@42 111 <p>Plan a real-input (r2c) or real-output (c2r), multi-dimensional DFT with
Chris@42 112 transform dimensions given by (<code>rank</code>, <code>dims</code>) over a
Chris@42 113 multi-dimensional vector (loop) of dimensions (<code>howmany_rank</code>,
Chris@42 114 <code>howmany_dims</code>). <code>dims</code> and <code>howmany_dims</code> should point
Chris@42 115 to <code>fftw_iodim</code> arrays of length <code>rank</code> and
Chris@42 116 <code>howmany_rank</code>, respectively. As for the basic and advanced
Chris@42 117 interfaces, an r2c transform is <code>FFTW_FORWARD</code> and a c2r transform
Chris@42 118 is <code>FFTW_BACKWARD</code>.
Chris@42 119 </p>
Chris@42 120 <p>The <em>last</em> dimension of <code>dims</code> is interpreted specially:
Chris@42 121 that dimension of the real array has size <code>dims[rank-1].n</code>, but
Chris@42 122 that dimension of the complex array has size <code>dims[rank-1].n/2+1</code>
Chris@42 123 (division rounded down). The strides, on the other hand, are taken to
Chris@42 124 be exactly as specified. It is up to the user to specify the strides
Chris@42 125 appropriately for the peculiar dimensions of the data, and we do not
Chris@42 126 guarantee that the planner will succeed (return non-<code>NULL</code>) for
Chris@42 127 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@42 128 for an in-place transform, each individual dimension should be able to
Chris@42 129 operate in place.)
Chris@42 130 <a name="index-in_002dplace-6"></a>
Chris@42 131 </p>
Chris@42 132
Chris@42 133 <p><code>in</code> and <code>out</code> point to the input and output arrays for r2c
Chris@42 134 and c2r transforms, respectively. For split arrays, <code>ri</code> and
Chris@42 135 <code>ii</code> point to the real and imaginary input arrays for a c2r
Chris@42 136 transform, and <code>ro</code> and <code>io</code> point to the real and imaginary
Chris@42 137 output arrays for an r2c transform. <code>in</code> and <code>ro</code> or
Chris@42 138 <code>ri</code> and <code>out</code> may be the same, indicating an in-place
Chris@42 139 transform. (In-place transforms where <code>in</code> and <code>io</code> or
Chris@42 140 <code>ii</code> and <code>out</code> are the same are not currently supported.)
Chris@42 141 </p>
Chris@42 142 <a name="index-flags-6"></a>
Chris@42 143 <p><code>flags</code> is a bitwise OR (&lsquo;<samp>|</samp>&rsquo;) of zero or more planner flags,
Chris@42 144 as defined in <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>.
Chris@42 145 </p>
Chris@42 146 <p>In-place transforms of rank greater than 1 are currently only
Chris@42 147 supported for interleaved arrays. For split arrays, the planner will
Chris@42 148 return <code>NULL</code>.
Chris@42 149 <a name="index-in_002dplace-7"></a>
Chris@42 150 </p>
Chris@42 151 <hr>
Chris@42 152 <div class="header">
Chris@42 153 <p>
Chris@42 154 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@42 155 </div>
Chris@42 156
Chris@42 157
Chris@42 158
Chris@42 159 </body>
Chris@42 160 </html>