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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Nov 2019 14:52:55 +0000
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3 <!-- This manual is for FFTW
4 (version 3.3.8, 24 May 2018).
5
6 Copyright (C) 2003 Matteo Frigo.
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8 Copyright (C) 2003 Massachusetts Institute of Technology.
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25 <title>FFTW 3.3.8: Advanced Real-data DFTs</title>
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37 <link href="Advanced-Real_002dto_002dreal-Transforms.html#Advanced-Real_002dto_002dreal-Transforms" rel="next" title="Advanced Real-to-real Transforms">
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71 <a name="Advanced-Real_002ddata-DFTs"></a>
72 <div class="header">
73 <p>
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>
75 </div>
76 <hr>
77 <a name="Advanced-Real_002ddata-DFTs-1"></a>
78 <h4 class="subsection">4.4.2 Advanced Real-data DFTs</h4>
79
80 <div class="example">
81 <pre class="example">fftw_plan fftw_plan_many_dft_r2c(int rank, const int *n, int howmany,
82 double *in, const int *inembed,
83 int istride, int idist,
84 fftw_complex *out, const int *onembed,
85 int ostride, int odist,
86 unsigned flags);
87 fftw_plan fftw_plan_many_dft_c2r(int rank, const int *n, int howmany,
88 fftw_complex *in, const int *inembed,
89 int istride, int idist,
90 double *out, const int *onembed,
91 int ostride, int odist,
92 unsigned flags);
93 </pre></div>
94 <a name="index-fftw_005fplan_005fmany_005fdft_005fr2c"></a>
95 <a name="index-fftw_005fplan_005fmany_005fdft_005fc2r"></a>
96
97 <p>Like <code>fftw_plan_many_dft</code>, these two functions add <code>howmany</code>,
98 <code>nembed</code>, <code>stride</code>, and <code>dist</code> parameters to the
99 <code>fftw_plan_dft_r2c</code> and <code>fftw_plan_dft_c2r</code> functions, but
100 otherwise behave the same as the basic interface.
101 </p>
102 <p>The interpretation of <code>howmany</code>, <code>stride</code>, and <code>dist</code> are
103 the same as for <code>fftw_plan_many_dft</code>, above. Note that the
104 <code>stride</code> and <code>dist</code> for the real array are in units of
105 <code>double</code>, and for the complex array are in units of
106 <code>fftw_complex</code>.
107 </p>
108 <p>If an <code>nembed</code> parameter is <code>NULL</code>, it is interpreted as what
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
110 the same as <code>n</code>, but with the last dimension cut roughly in half.
111 For the real array, the size is assumed to be <code>n</code> if the transform
112 is out-of-place, or <code>n</code> with the last dimension &ldquo;padded&rdquo; if the
113 transform is in-place.
114 </p>
115 <p>If an <code>nembed</code> parameter is non-<code>NULL</code>, it is interpreted as
116 the physical size of the corresponding array, in row-major order, just
117 as for <code>fftw_plan_many_dft</code>. In this case, each dimension of
118 <code>nembed</code> should be <code>&gt;=</code> what it would be in the basic
119 interface (e.g. the halved or padded <code>n</code>).
120 </p>
121 <p>Arrays <code>n</code>, <code>inembed</code>, and <code>onembed</code> are not used after
122 this function returns. You can safely free or reuse them.
123 </p>
124 <hr>
125 <div class="header">
126 <p>
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>
128 </div>
129
130
131
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133 </html>