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Add null config files
author Chris Cannam
date Mon, 02 Mar 2020 14:03:47 +0000
parents d0c2a83c1364
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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.
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Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: Advanced Real-data DFTs</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Advanced 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="Advanced-Interface.html#Advanced-Interface" rel="up" title="Advanced Interface">
Chris@82 37 <link href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" rel="next" title="Advanced Real-to-real Transforms">
Chris@82 38 <link href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" rel="prev" title="Advanced Complex DFTs">
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Chris@82 65 </style>
Chris@82 66
Chris@82 67
Chris@82 68 </head>
Chris@82 69
Chris@82 70 <body lang="en">
Chris@82 71 <a name="Advanced-Real_002ddata-DFTs"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 Next: <a href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Advanced Real-to-real Transforms</a>, Previous: <a href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" accesskey="p" rel="prev">Advanced Complex DFTs</a>, Up: <a href="Advanced-Interface.html#Advanced-Interface" accesskey="u" rel="up">Advanced 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="Advanced-Real_002ddata-DFTs-1"></a>
Chris@82 78 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
Chris@82 79
Chris@82 80 <div class="example">
Chris@82 81 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
Chris@82 82 double *in, const int *inembed,
Chris@82 83 int istride, int idist,
Chris@82 84 fftw_complex *out, const int *onembed,
Chris@82 85 int ostride, int odist,
Chris@82 86 unsigned flags);
Chris@82 87 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
Chris@82 88 fftw_complex *in, const int *inembed,
Chris@82 89 int istride, int idist,
Chris@82 90 double *out, const int *onembed,
Chris@82 91 int ostride, int odist,
Chris@82 92 unsigned flags);
Chris@82 93 </pre></div>
Chris@82 94 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
Chris@82 95 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
Chris@82 96
Chris@82 97 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
Chris@82 98 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
Chris@82 99 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
Chris@82 100 otherwise behave the same as the basic interface.
Chris@82 101 </p>
Chris@82 102 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
Chris@82 103 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
Chris@82 104 <code>stride</code> and <code>dist</code> for the real array are in units of
Chris@82 105 <code>double</code>, and for the complex array are in units of
Chris@82 106 <code>fftw_complex</code>.
Chris@82 107 </p>
Chris@82 108 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
Chris@82 109 it would be in the basic interface, as described in <a href="Real_002ddata-DFT-Array-Format.html#Real_002ddata-DFT-Array-Format">Real-data DFT Array Format</a>. That is, for the complex array the size is assumed to be
Chris@82 110 the same as <code>n</code>, but with the last dimension cut roughly in half.
Chris@82 111 For the real array, the size is assumed to be <code>n</code> if the transform
Chris@82 112 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
Chris@82 113 transform is in-place.
Chris@82 114 </p>
Chris@82 115 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
Chris@82 116 the physical size of the corresponding array, in row-major order, just
Chris@82 117 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
Chris@82 118 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
Chris@82 119 interface (e.g. the halved or padded <code>n</code>).
Chris@82 120 </p>
Chris@82 121 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
Chris@82 122 this function returns. You can safely free or reuse them.
Chris@82 123 </p>
Chris@82 124 <hr>
Chris@82 125 <div class="header">
Chris@82 126 <p>
Chris@82 127 Next: <a href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" accesskey="n" rel="next">Advanced Real-to-real Transforms</a>, Previous: <a href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" accesskey="p" rel="prev">Advanced Complex DFTs</a>, Up: <a href="Advanced-Interface.html#Advanced-Interface" accesskey="u" rel="up">Advanced 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@82 128 </div>
Chris@82 129
Chris@82 130
Chris@82 131
Chris@82 132 </body>
Chris@82 133 </html>