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Add null config files
author Chris Cannam <cannam@all-day-breakfast.com>
date Mon, 02 Mar 2020 14:03:47 +0000
parents 7867fa7e1b6b
children
rev   line source
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cannam@127 3 <!-- This manual is for FFTW
cannam@127 4 (version 3.3.5, 30 July 2016).
cannam@127 5
cannam@127 6 Copyright (C) 2003 Matteo Frigo.
cannam@127 7
cannam@127 8 Copyright (C) 2003 Massachusetts Institute of Technology.
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cannam@127 24 <head>
cannam@127 25 <title>FFTW 3.3.5: Advanced Real-data DFTs</title>
cannam@127 26
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cannam@127 38 <link href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs" rel="prev" title="Advanced Complex DFTs">
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cannam@127 69 </head>
cannam@127 70
cannam@127 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
cannam@127 72 <a name="Advanced-Real_002ddata-DFTs"></a>
cannam@127 73 <div class="header">
cannam@127 74 <p>
cannam@127 75 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>
cannam@127 76 </div>
cannam@127 77 <hr>
cannam@127 78 <a name="Advanced-Real_002ddata-DFTs-1"></a>
cannam@127 79 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
cannam@127 80
cannam@127 81 <div class="example">
cannam@127 82 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
cannam@127 83 double *in, const int *inembed,
cannam@127 84 int istride, int idist,
cannam@127 85 fftw_complex *out, const int *onembed,
cannam@127 86 int ostride, int odist,
cannam@127 87 unsigned flags);
cannam@127 88 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
cannam@127 89 fftw_complex *in, const int *inembed,
cannam@127 90 int istride, int idist,
cannam@127 91 double *out, const int *onembed,
cannam@127 92 int ostride, int odist,
cannam@127 93 unsigned flags);
cannam@127 94 </pre></div>
cannam@127 95 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
cannam@127 96 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
cannam@127 97
cannam@127 98 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
cannam@127 99 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
cannam@127 100 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
cannam@127 101 otherwise behave the same as the basic interface.
cannam@127 102 </p>
cannam@127 103 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
cannam@127 104 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
cannam@127 105 <code>stride</code> and <code>dist</code> for the real array are in units of
cannam@127 106 <code>double</code>, and for the complex array are in units of
cannam@127 107 <code>fftw_complex</code>.
cannam@127 108 </p>
cannam@127 109 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
cannam@127 110 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
cannam@127 111 the same as <code>n</code>, but with the last dimension cut roughly in half.
cannam@127 112 For the real array, the size is assumed to be <code>n</code> if the transform
cannam@127 113 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
cannam@127 114 transform is in-place.
cannam@127 115 </p>
cannam@127 116 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
cannam@127 117 the physical size of the corresponding array, in row-major order, just
cannam@127 118 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
cannam@127 119 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
cannam@127 120 interface (e.g. the halved or padded <code>n</code>).
cannam@127 121 </p>
cannam@127 122 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
cannam@127 123 this function returns. You can safely free or reuse them.
cannam@127 124 </p>
cannam@127 125 <hr>
cannam@127 126 <div class="header">
cannam@127 127 <p>
cannam@127 128 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>
cannam@127 129 </div>
cannam@127 130
cannam@127 131
cannam@127 132
cannam@127 133 </body>
cannam@127 134 </html>