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| author | Geogaddi\David <d.m.ronan@qmul.ac.uk> |
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| date | Thu, 09 Jul 2015 01:12:16 +0100 |
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| 1 <html lang="en"> | |
| 2 <head> | |
| 3 <title>Guru Real-data DFTs - FFTW 3.2.1</title> | |
| 4 <meta http-equiv="Content-Type" content="text/html"> | |
| 5 <meta name="description" content="FFTW 3.2.1"> | |
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| 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 3.2.1, 5 February 2009). | |
| 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 | |
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| 46 </head> | |
| 47 <body> | |
| 48 <div class="node"> | |
| 49 <p> | |
| 50 <a name="Guru-Real-data-DFTs"></a> | |
| 51 <a name="Guru-Real_002ddata-DFTs"></a> | |
| 52 Next: <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: <a rel="previous" accesskey="p" href="Guru-Complex-DFTs.html#Guru-Complex-DFTs">Guru Complex DFTs</a>, | |
| 54 Up: <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-243"></a><a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fr2c-244"></a><a name="index-fftw_005fplan_005fguru_005fdft_005fc2r-245"></a><a name="index-fftw_005fplan_005fguru_005fsplit_005fdft_005fc2r-246"></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-247"></a> | |
| 105 <code>in</code> and <code>out</code> point to the input and output arrays for r2c | |
| 106 and c2r transforms, respectively. For split arrays, <code>ri</code> and | |
| 107 <code>ii</code> point to the real and imaginary input arrays for a c2r | |
| 108 transform, and <code>ro</code> and <code>io</code> point to the real and imaginary | |
| 109 output arrays for an r2c transform. <code>in</code> and <code>ro</code> or | |
| 110 <code>ri</code> and <code>out</code> may be the same, indicating an in-place | |
| 111 transform. (In-place transforms where <code>in</code> and <code>io</code> or | |
| 112 <code>ii</code> and <code>out</code> are the same are not currently supported.) | |
| 113 | |
| 114 <p><a name="index-flags-248"></a><code>flags</code> is a bitwise OR (`<samp><span class="samp">|</span></samp>') of zero or more planner flags, | |
| 115 as defined in <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>. | |
| 116 | |
| 117 <p>In-place transforms of rank greater than 1 are currently only | |
| 118 supported for interleaved arrays. For split arrays, the planner will | |
| 119 return <code>NULL</code>. | |
| 120 <a name="index-in_002dplace-249"></a> | |
| 121 <!-- =========> --> | |
| 122 | |
| 123 </body></html> | |
| 124 |