Mercurial > hg > sv-dependency-builds

comparison src/fftw-3.3.3/doc/html/Guru-Real_002ddata-DFTs.html @ 95:89f5e221ed7b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add FFTW3
author Chris Cannam <cannam@all-day-breakfast.com>
date Wed, 20 Mar 2013 15:35:50 +0000
parents
children
comparison
equal deleted inserted replaced
94:d278df1123f9 95:89f5e221ed7b
1 <html lang="en">
2 <head>
3 <title>Guru Real-data DFTs - FFTW 3.3.3</title>
4 <meta http-equiv="Content-Type" content="text/html">
5 <meta name="description" content="FFTW 3.3.3">
6 <meta name="generator" content="makeinfo 4.13">
7 <link title="Top" rel="start" href="index.html#Top">
8 <link rel="up" href="Guru-Interface.html#Guru-Interface" title="Guru Interface">
9 <link rel="prev" href="Guru-Complex-DFTs.html#Guru-Complex-DFTs" title="Guru Complex DFTs">
10 <link rel="next" href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms" title="Guru Real-to-real Transforms">
11 <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
12 <!--
13 This manual is for FFTW
14 (version 3.3.3, 25 November 2012).
15
16 Copyright (C) 2003 Matteo Frigo.
17
18 Copyright (C) 2003 Massachusetts Institute of Technology.
19
20 Permission is granted to make and distribute verbatim copies of
21 this manual provided the copyright notice and this permission
22 notice are preserved on all copies.
23
24 Permission is granted to copy and distribute modified versions of
25 this manual under the conditions for verbatim copying, provided
26 that the entire resulting derived work is distributed under the
27 terms of a permission notice identical to this one.
28
29 Permission is granted to copy and distribute translations of this
30 manual into another language, under the above conditions for
31 modified versions, except that this permission notice may be
32 stated in a translation approved by the Free Software Foundation.
33 -->
34 <meta http-equiv="Content-Style-Type" content="text/css">
35 <style type="text/css"><!--
36 pre.display { font-family:inherit }
37 pre.format { font-family:inherit }
38 pre.smalldisplay { font-family:inherit; font-size:smaller }
39 pre.smallformat { font-family:inherit; font-size:smaller }
40 pre.smallexample { font-size:smaller }
41 pre.smalllisp { font-size:smaller }
42 span.sc { font-variant:small-caps }
43 span.roman { font-family:serif; font-weight:normal; }
44 span.sansserif { font-family:sans-serif; font-weight:normal; }
45 --></style>
46 </head>
47 <body>
48 <div class="node">
49 <a name="Guru-Real-data-DFTs"></a>
50 <a name="Guru-Real_002ddata-DFTs"></a>
51 <p>
52 Next:&nbsp;<a rel="next" accesskey="n" href="Guru-Real_002dto_002dreal-Transforms.html#Guru-Real_002dto_002dreal-Transforms">Guru Real-to-real Transforms</a>,
53 Previous:&nbsp;<a rel="previous" accesskey="p" href="Guru-Complex-DFTs.html#Guru-Complex-DFTs">Guru Complex DFTs</a>,
54 Up:&nbsp;<a rel="up" accesskey="u" href="Guru-Interface.html#Guru-Interface">Guru Interface</a>
55 <hr>
56 </div>
57
58 <h4 class="subsection">4.5.4 Guru Real-data DFTs</h4>
59
60 <pre class="example"> fftw_plan fftw_plan_guru_dft_r2c(
61 int rank, const fftw_iodim *dims,
62 int howmany_rank, const fftw_iodim *howmany_dims,
63 double *in, fftw_complex *out,
64 unsigned flags);
65
66 fftw_plan fftw_plan_guru_split_dft_r2c(
67 int rank, const fftw_iodim *dims,
68 int howmany_rank, const fftw_iodim *howmany_dims,
69 double *in, double *ro, double *io,
70 unsigned flags);
71
72 fftw_plan fftw_plan_guru_dft_c2r(
73 int rank, const fftw_iodim *dims,
74 int howmany_rank, const fftw_iodim *howmany_dims,
75 fftw_complex *in, double *out,
76 unsigned flags);
77
78 fftw_plan fftw_plan_guru_split_dft_c2r(
79 int rank, const fftw_iodim *dims,
80 int howmany_rank, const fftw_iodim *howmany_dims,
81 double *ri, double *ii, double *out,
82 unsigned flags);
83 </pre>
84 <p><a name="index-fftw_005fplan_005fguru_005fdft_005fr2c-251"></a><a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fr2c-252"></a><a name="index-fftw_005fplan_005fguru_005fdft_005fc2r-253"></a><a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fc2r-254"></a>
85 Plan a real-input (r2c) or real-output (c2r), multi-dimensional DFT with
86 transform dimensions given by (<code>rank</code>, <code>dims</code>) over a
87 multi-dimensional vector (loop) of dimensions (<code>howmany_rank</code>,
88 <code>howmany_dims</code>). <code>dims</code> and <code>howmany_dims</code> should point
89 to <code>fftw_iodim</code> arrays of length <code>rank</code> and
90 <code>howmany_rank</code>, respectively. As for the basic and advanced
91 interfaces, an r2c transform is <code>FFTW_FORWARD</code> and a c2r transform
92 is <code>FFTW_BACKWARD</code>.
93
94 <p>The <em>last</em> dimension of <code>dims</code> is interpreted specially:
95 that dimension of the real array has size <code>dims[rank-1].n</code>, but
96 that dimension of the complex array has size <code>dims[rank-1].n/2+1</code>
97 (division rounded down). The strides, on the other hand, are taken to
98 be exactly as specified. It is up to the user to specify the strides
99 appropriately for the peculiar dimensions of the data, and we do not
100 guarantee that the planner will succeed (return non-<code>NULL</code>) for
101 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,
102 for an in-place transform, each individual dimension should be able to
103 operate in place.)
104 <a name="index-in_002dplace-255"></a>
105
106 <p><code>in</code> and <code>out</code> point to the input and output arrays for r2c
107 and c2r transforms, respectively. For split arrays, <code>ri</code> and
108 <code>ii</code> point to the real and imaginary input arrays for a c2r
109 transform, and <code>ro</code> and <code>io</code> point to the real and imaginary
110 output arrays for an r2c transform. <code>in</code> and <code>ro</code> or
111 <code>ri</code> and <code>out</code> may be the same, indicating an in-place
112 transform. (In-place transforms where <code>in</code> and <code>io</code> or
113 <code>ii</code> and <code>out</code> are the same are not currently supported.)
114
115 <p><a name="index-flags-256"></a><code>flags</code> is a bitwise OR (&lsquo;<samp><span class="samp">|</span></samp>&rsquo;) of zero or more planner flags,
116 as defined in <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>.
117
118 <p>In-place transforms of rank greater than 1 are currently only
119 supported for interleaved arrays. For split arrays, the planner will
120 return <code>NULL</code>.
121 <a name="index-in_002dplace-257"></a>
122 <!-- =========> -->
123
124 </body></html>
125