Mercurial > hg > sv-dependency-builds

annotate src/fftw-3.3.5/doc/html/Basic-distributed_002dtranspose-interface.html @ 83:ae30d91d2ffe

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 2cd0e3b3e1fd
children
rev   line source
Chris@42 1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
Chris@42 2 <html>
Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
Chris@42 5
Chris@42 6 Copyright (C) 2003 Matteo Frigo.
Chris@42 7
Chris@42 8 Copyright (C) 2003 Massachusetts Institute of Technology.
Chris@42 9
Chris@42 10 Permission is granted to make and distribute verbatim copies of this
Chris@42 11 manual provided the copyright notice and this permission notice are
Chris@42 12 preserved on all copies.
Chris@42 13
Chris@42 14 Permission is granted to copy and distribute modified versions of this
Chris@42 15 manual under the conditions for verbatim copying, provided that the
Chris@42 16 entire resulting derived work is distributed under the terms of a
Chris@42 17 permission notice identical to this one.
Chris@42 18
Chris@42 19 Permission is granted to copy and distribute translations of this manual
Chris@42 20 into another language, under the above conditions for modified versions,
Chris@42 21 except that this permission notice may be stated in a translation
Chris@42 22 approved by the Free Software Foundation. -->
Chris@42 23 <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Basic distributed-transpose interface</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Basic distributed-transpose interface">
Chris@42 28 <meta name="keywords" content="FFTW 3.3.5: Basic distributed-transpose interface">
Chris@42 29 <meta name="resource-type" content="document">
Chris@42 30 <meta name="distribution" content="global">
Chris@42 31 <meta name="Generator" content="makeinfo">
Chris@42 32 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Chris@42 33 <link href="index.html#Top" rel="start" title="Top">
Chris@42 34 <link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" rel="up" title="FFTW MPI Transposes">
Chris@42 37 <link href="Advanced-distributed_002dtranspose-interface.html#Advanced-distributed_002dtranspose-interface" rel="next" title="Advanced distributed-transpose interface">
Chris@42 38 <link href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" rel="prev" title="FFTW MPI Transposes">
Chris@42 39 <style type="text/css">
Chris@42 40 <!--
Chris@42 41 a.summary-letter {text-decoration: none}
Chris@42 42 blockquote.smallquotation {font-size: smaller}
Chris@42 43 div.display {margin-left: 3.2em}
Chris@42 44 div.example {margin-left: 3.2em}
Chris@42 45 div.indentedblock {margin-left: 3.2em}
Chris@42 46 div.lisp {margin-left: 3.2em}
Chris@42 47 div.smalldisplay {margin-left: 3.2em}
Chris@42 48 div.smallexample {margin-left: 3.2em}
Chris@42 49 div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
Chris@42 50 div.smalllisp {margin-left: 3.2em}
Chris@42 51 kbd {font-style:oblique}
Chris@42 52 pre.display {font-family: inherit}
Chris@42 53 pre.format {font-family: inherit}
Chris@42 54 pre.menu-comment {font-family: serif}
Chris@42 55 pre.menu-preformatted {font-family: serif}
Chris@42 56 pre.smalldisplay {font-family: inherit; font-size: smaller}
Chris@42 57 pre.smallexample {font-size: smaller}
Chris@42 58 pre.smallformat {font-family: inherit; font-size: smaller}
Chris@42 59 pre.smalllisp {font-size: smaller}
Chris@42 60 span.nocodebreak {white-space:nowrap}
Chris@42 61 span.nolinebreak {white-space:nowrap}
Chris@42 62 span.roman {font-family:serif; font-weight:normal}
Chris@42 63 span.sansserif {font-family:sans-serif; font-weight:normal}
Chris@42 64 ul.no-bullet {list-style: none}
Chris@42 65 -->
Chris@42 66 </style>
Chris@42 67
Chris@42 68
Chris@42 69 </head>
Chris@42 70
Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Basic-distributed_002dtranspose-interface"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Next: <a href="Advanced-distributed_002dtranspose-interface.html#Advanced-distributed_002dtranspose-interface" accesskey="n" rel="next">Advanced distributed-transpose interface</a>, Previous: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="p" rel="prev">FFTW MPI Transposes</a>, Up: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="u" rel="up">FFTW MPI Transposes</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@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Basic-distributed_002dtranspose-interface-1"></a>
Chris@42 79 <h4 class="subsection">6.7.1 Basic distributed-transpose interface</h4>
Chris@42 80
Chris@42 81 <p>In particular, suppose that we have an <code>n0</code> by <code>n1</code> array in
Chris@42 82 row-major order, block-distributed across the <code>n0</code> dimension. To
Chris@42 83 transpose this into an <code>n1</code> by <code>n0</code> array block-distributed
Chris@42 84 across the <code>n1</code> dimension, we would create a plan by calling the
Chris@42 85 following function:
Chris@42 86 </p>
Chris@42 87 <div class="example">
Chris@42 88 <pre class="example">fftw_plan fftw_mpi_plan_transpose(ptrdiff_t n0, ptrdiff_t n1,
Chris@42 89 double *in, double *out,
Chris@42 90 MPI_Comm comm, unsigned flags);
Chris@42 91 </pre></div>
Chris@42 92 <a name="index-fftw_005fmpi_005fplan_005ftranspose"></a>
Chris@42 93
Chris@42 94 <p>The input and output arrays (<code>in</code> and <code>out</code>) can be the
Chris@42 95 same. The transpose is actually executed by calling
Chris@42 96 <code>fftw_execute</code> on the plan, as usual.
Chris@42 97 <a name="index-fftw_005fexecute-3"></a>
Chris@42 98 </p>
Chris@42 99
Chris@42 100 <p>The <code>flags</code> are the usual FFTW planner flags, but support
Chris@42 101 two additional flags: <code>FFTW_MPI_TRANSPOSED_OUT</code> and/or
Chris@42 102 <code>FFTW_MPI_TRANSPOSED_IN</code>. What these flags indicate, for
Chris@42 103 transpose plans, is that the output and/or input, respectively, are
Chris@42 104 <em>locally</em> transposed. That is, on each process input data is
Chris@42 105 normally stored as a <code>local_n0</code> by <code>n1</code> array in row-major
Chris@42 106 order, but for an <code>FFTW_MPI_TRANSPOSED_IN</code> plan the input data is
Chris@42 107 stored as <code>n1</code> by <code>local_n0</code> in row-major order. Similarly,
Chris@42 108 <code>FFTW_MPI_TRANSPOSED_OUT</code> means that the output is <code>n0</code> by
Chris@42 109 <code>local_n1</code> instead of <code>local_n1</code> by <code>n0</code>.
Chris@42 110 <a name="index-FFTW_005fMPI_005fTRANSPOSED_005fOUT-1"></a>
Chris@42 111 <a name="index-FFTW_005fMPI_005fTRANSPOSED_005fIN-1"></a>
Chris@42 112 </p>
Chris@42 113
Chris@42 114 <p>To determine the local size of the array on each process before and
Chris@42 115 after the transpose, as well as the amount of storage that must be
Chris@42 116 allocated, one should call <code>fftw_mpi_local_size_2d_transposed</code>,
Chris@42 117 just as for a 2d DFT as described in the previous section:
Chris@42 118 <a name="index-data-distribution-4"></a>
Chris@42 119 </p>
Chris@42 120 <div class="example">
Chris@42 121 <pre class="example">ptrdiff_t fftw_mpi_local_size_2d_transposed
Chris@42 122 (ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
Chris@42 123 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@42 124 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@42 125 </pre></div>
Chris@42 126 <a name="index-fftw_005fmpi_005flocal_005fsize_005f2d_005ftransposed"></a>
Chris@42 127
Chris@42 128 <p>Again, the return value is the local storage to allocate, which in
Chris@42 129 this case is the number of <em>real</em> (<code>double</code>) values rather
Chris@42 130 than complex numbers as in the previous examples.
Chris@42 131 </p>
Chris@42 132 <hr>
Chris@42 133 <div class="header">
Chris@42 134 <p>
Chris@42 135 Next: <a href="Advanced-distributed_002dtranspose-interface.html#Advanced-distributed_002dtranspose-interface" accesskey="n" rel="next">Advanced distributed-transpose interface</a>, Previous: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="p" rel="prev">FFTW MPI Transposes</a>, Up: <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" accesskey="u" rel="up">FFTW MPI Transposes</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@42 136 </div>
Chris@42 137
Chris@42 138
Chris@42 139
Chris@42 140 </body>
Chris@42 141 </html>