Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.8/doc/html/Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html @ 82:d0c2a83c1364

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
parents
children
rev   line source
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.
Chris@82 9
Chris@82 10 Permission is granted to make and distribute verbatim copies of this
Chris@82 11 manual provided the copyright notice and this permission notice are
Chris@82 12 preserved on all copies.
Chris@82 13
Chris@82 14 Permission is granted to copy and distribute modified versions of this
Chris@82 15 manual under the conditions for verbatim copying, provided that the
Chris@82 16 entire resulting derived work is distributed under the terms of a
Chris@82 17 permission notice identical to this one.
Chris@82 18
Chris@82 19 Permission is granted to copy and distribute translations of this manual
Chris@82 20 into another language, under the above conditions for modified versions,
Chris@82 21 except that this permission notice may be stated in a translation
Chris@82 22 approved by the Free Software Foundation. -->
Chris@82 23 <!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: Other Multi-dimensional Real-data MPI Transforms</title>
Chris@82 26
Chris@82 27 <meta name="description" content="FFTW 3.3.8: Other Multi-dimensional Real-data MPI Transforms">
Chris@82 28 <meta name="keywords" content="FFTW 3.3.8: Other Multi-dimensional Real-data MPI Transforms">
Chris@82 29 <meta name="resource-type" content="document">
Chris@82 30 <meta name="distribution" content="global">
Chris@82 31 <meta name="Generator" content="makeinfo">
Chris@82 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Chris@82 33 <link href="index.html#Top" rel="start" title="Top">
Chris@82 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@82 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@82 36 <link href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" rel="up" title="Distributed-memory FFTW with MPI">
Chris@82 37 <link href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" rel="next" title="FFTW MPI Transposes">
Chris@82 38 <link href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data" rel="prev" title="Multi-dimensional MPI DFTs of Real Data">
Chris@82 39 <style type="text/css">
Chris@82 40 <!--
Chris@82 41 a.summary-letter {text-decoration: none}
Chris@82 42 blockquote.indentedblock {margin-right: 0em}
Chris@82 43 blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
Chris@82 44 blockquote.smallquotation {font-size: smaller}
Chris@82 45 div.display {margin-left: 3.2em}
Chris@82 46 div.example {margin-left: 3.2em}
Chris@82 47 div.lisp {margin-left: 3.2em}
Chris@82 48 div.smalldisplay {margin-left: 3.2em}
Chris@82 49 div.smallexample {margin-left: 3.2em}
Chris@82 50 div.smalllisp {margin-left: 3.2em}
Chris@82 51 kbd {font-style: oblique}
Chris@82 52 pre.display {font-family: inherit}
Chris@82 53 pre.format {font-family: inherit}
Chris@82 54 pre.menu-comment {font-family: serif}
Chris@82 55 pre.menu-preformatted {font-family: serif}
Chris@82 56 pre.smalldisplay {font-family: inherit; font-size: smaller}
Chris@82 57 pre.smallexample {font-size: smaller}
Chris@82 58 pre.smallformat {font-family: inherit; font-size: smaller}
Chris@82 59 pre.smalllisp {font-size: smaller}
Chris@82 60 span.nolinebreak {white-space: nowrap}
Chris@82 61 span.roman {font-family: initial; font-weight: normal}
Chris@82 62 span.sansserif {font-family: sans-serif; font-weight: normal}
Chris@82 63 ul.no-bullet {list-style: none}
Chris@82 64 -->
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="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 Next: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="n" rel="next">FFTW MPI Transposes</a>, Previous: <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data" accesskey="p" rel="prev">Multi-dimensional MPI DFTs of Real Data</a>, Up: <a href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" accesskey="u" rel="up">Distributed-memory FFTW with MPI</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="Other-multi_002ddimensional-Real_002dData-MPI-Transforms"></a>
Chris@82 78 <h3 class="section">6.6 Other multi-dimensional Real-Data MPI Transforms</h3>
Chris@82 79
Chris@82 80 <a name="index-r2r-3"></a>
Chris@82 81 <p>FFTW&rsquo;s MPI interface also supports multi-dimensional &lsquo;<samp>r2r</samp>&rsquo;
Chris@82 82 transforms of all kinds supported by the serial interface
Chris@82 83 (e.g. discrete cosine and sine transforms, discrete Hartley
Chris@82 84 transforms, etc.). Only multi-dimensional &lsquo;<samp>r2r</samp>&rsquo; transforms, not
Chris@82 85 one-dimensional transforms, are currently parallelized.
Chris@82 86 </p>
Chris@82 87 <a name="index-fftw_005fr2r_005fkind-1"></a>
Chris@82 88 <p>These are used much like the multidimensional complex DFTs discussed
Chris@82 89 above, except that the data is real rather than complex, and one needs
Chris@82 90 to pass an r2r transform kind (<code>fftw_r2r_kind</code>) for each
Chris@82 91 dimension as in the serial FFTW (see <a href="More-DFTs-of-Real-Data.html#More-DFTs-of-Real-Data">More DFTs of Real Data</a>).
Chris@82 92 </p>
Chris@82 93 <p>For example, one might perform a two-dimensional L&nbsp;&times;&nbsp;M
Chris@82 94 that is
Chris@82 95 an REDFT10 (DCT-II) in the first dimension and an RODFT10 (DST-II) in
Chris@82 96 the second dimension with code like:
Chris@82 97 </p>
Chris@82 98 <div class="example">
Chris@82 99 <pre class="example"> const ptrdiff_t L = ..., M = ...;
Chris@82 100 fftw_plan plan;
Chris@82 101 double *data;
Chris@82 102 ptrdiff_t alloc_local, local_n0, local_0_start, i, j;
Chris@82 103
Chris@82 104 /* <span class="roman">get local data size and allocate</span> */
Chris@82 105 alloc_local = fftw_mpi_local_size_2d(L, M, MPI_COMM_WORLD,
Chris@82 106 &amp;local_n0, &amp;local_0_start);
Chris@82 107 data = fftw_alloc_real(alloc_local);
Chris@82 108
Chris@82 109 /* <span class="roman">create plan for in-place REDFT10 x RODFT10</span> */
Chris@82 110 plan = fftw_mpi_plan_r2r_2d(L, M, data, data, MPI_COMM_WORLD,
Chris@82 111 FFTW_REDFT10, FFTW_RODFT10, FFTW_MEASURE);
Chris@82 112
Chris@82 113 /* <span class="roman">initialize data to some function</span> my_function(x,y) */
Chris@82 114 for (i = 0; i &lt; local_n0; ++i) for (j = 0; j &lt; M; ++j)
Chris@82 115 data[i*M + j] = my_function(local_0_start + i, j);
Chris@82 116
Chris@82 117 /* <span class="roman">compute transforms, in-place, as many times as desired</span> */
Chris@82 118 fftw_execute(plan);
Chris@82 119
Chris@82 120 fftw_destroy_plan(plan);
Chris@82 121 </pre></div>
Chris@82 122
Chris@82 123 <a name="index-fftw_005falloc_005freal-3"></a>
Chris@82 124 <p>Notice that we use the same &lsquo;<samp>local_size</samp>&rsquo; functions as we did for
Chris@82 125 complex data, only now we interpret the sizes in terms of real rather
Chris@82 126 than complex values, and correspondingly use <code>fftw_alloc_real</code>.
Chris@82 127 </p>
Chris@82 128
Chris@82 129
Chris@82 130
Chris@82 131 </body>
Chris@82 132 </html>