mirror of
https://github.com/tildearrow/furnace.git
synced 2024-12-04 18:27:25 +00:00
129 lines
6.3 KiB
HTML
129 lines
6.3 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This manual is for FFTW
|
|
(version 3.3.10, 10 December 2020).
|
|
|
|
Copyright (C) 2003 Matteo Frigo.
|
|
|
|
Copyright (C) 2003 Massachusetts Institute of Technology.
|
|
|
|
Permission is granted to make and distribute verbatim copies of this
|
|
manual provided the copyright notice and this permission notice are
|
|
preserved on all copies.
|
|
|
|
Permission is granted to copy and distribute modified versions of this
|
|
manual under the conditions for verbatim copying, provided that the
|
|
entire resulting derived work is distributed under the terms of a
|
|
permission notice identical to this one.
|
|
|
|
Permission is granted to copy and distribute translations of this manual
|
|
into another language, under the above conditions for modified versions,
|
|
except that this permission notice may be stated in a translation
|
|
approved by the Free Software Foundation. -->
|
|
<!-- Created by GNU Texinfo 6.7, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<title>Basic distributed-transpose interface (FFTW 3.3.10)</title>
|
|
|
|
<meta name="description" content="Basic distributed-transpose interface (FFTW 3.3.10)">
|
|
<meta name="keywords" content="Basic distributed-transpose interface (FFTW 3.3.10)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<link href="index.html" rel="start" title="Top">
|
|
<link href="Concept-Index.html" rel="index" title="Concept Index">
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
|
<link href="FFTW-MPI-Transposes.html" rel="up" title="FFTW MPI Transposes">
|
|
<link href="Advanced-distributed_002dtranspose-interface.html" rel="next" title="Advanced distributed-transpose interface">
|
|
<link href="FFTW-MPI-Transposes.html" rel="prev" title="FFTW MPI Transposes">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<span id="Basic-distributed_002dtranspose-interface"></span><div class="header">
|
|
<p>
|
|
Next: <a href="Advanced-distributed_002dtranspose-interface.html" accesskey="n" rel="next">Advanced distributed-transpose interface</a>, Previous: <a href="FFTW-MPI-Transposes.html" accesskey="p" rel="prev">FFTW MPI Transposes</a>, Up: <a href="FFTW-MPI-Transposes.html" accesskey="u" rel="up">FFTW MPI Transposes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<span id="Basic-distributed_002dtranspose-interface-1"></span><h4 class="subsection">6.7.1 Basic distributed-transpose interface</h4>
|
|
|
|
<p>In particular, suppose that we have an <code>n0</code> by <code>n1</code> array in
|
|
row-major order, block-distributed across the <code>n0</code> dimension. To
|
|
transpose this into an <code>n1</code> by <code>n0</code> array block-distributed
|
|
across the <code>n1</code> dimension, we would create a plan by calling the
|
|
following function:
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">fftw_plan fftw_mpi_plan_transpose(ptrdiff_t n0, ptrdiff_t n1,
|
|
double *in, double *out,
|
|
MPI_Comm comm, unsigned flags);
|
|
</pre></div>
|
|
<span id="index-fftw_005fmpi_005fplan_005ftranspose"></span>
|
|
|
|
<p>The input and output arrays (<code>in</code> and <code>out</code>) can be the
|
|
same. The transpose is actually executed by calling
|
|
<code>fftw_execute</code> on the plan, as usual.
|
|
<span id="index-fftw_005fexecute-3"></span>
|
|
</p>
|
|
|
|
<p>The <code>flags</code> are the usual FFTW planner flags, but support
|
|
two additional flags: <code>FFTW_MPI_TRANSPOSED_OUT</code> and/or
|
|
<code>FFTW_MPI_TRANSPOSED_IN</code>. What these flags indicate, for
|
|
transpose plans, is that the output and/or input, respectively, are
|
|
<em>locally</em> transposed. That is, on each process input data is
|
|
normally stored as a <code>local_n0</code> by <code>n1</code> array in row-major
|
|
order, but for an <code>FFTW_MPI_TRANSPOSED_IN</code> plan the input data is
|
|
stored as <code>n1</code> by <code>local_n0</code> in row-major order. Similarly,
|
|
<code>FFTW_MPI_TRANSPOSED_OUT</code> means that the output is <code>n0</code> by
|
|
<code>local_n1</code> instead of <code>local_n1</code> by <code>n0</code>.
|
|
<span id="index-FFTW_005fMPI_005fTRANSPOSED_005fOUT-1"></span>
|
|
<span id="index-FFTW_005fMPI_005fTRANSPOSED_005fIN-1"></span>
|
|
</p>
|
|
|
|
<p>To determine the local size of the array on each process before and
|
|
after the transpose, as well as the amount of storage that must be
|
|
allocated, one should call <code>fftw_mpi_local_size_2d_transposed</code>,
|
|
just as for a 2d DFT as described in the previous section:
|
|
<span id="index-data-distribution-4"></span>
|
|
</p>
|
|
<div class="example">
|
|
<pre class="example">ptrdiff_t fftw_mpi_local_size_2d_transposed
|
|
(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
|
|
ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
|
|
ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
|
|
</pre></div>
|
|
<span id="index-fftw_005fmpi_005flocal_005fsize_005f2d_005ftransposed"></span>
|
|
|
|
<p>Again, the return value is the local storage to allocate, which in
|
|
this case is the number of <em>real</em> (<code>double</code>) values rather
|
|
than complex numbers as in the previous examples.
|
|
</p>
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Advanced-distributed_002dtranspose-interface.html" accesskey="n" rel="next">Advanced distributed-transpose interface</a>, Previous: <a href="FFTW-MPI-Transposes.html" accesskey="p" rel="prev">FFTW MPI Transposes</a>, Up: <a href="FFTW-MPI-Transposes.html" accesskey="u" rel="up">FFTW MPI Transposes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|