122 lines
5.5 KiB
HTML
122 lines
5.5 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>Other Multi-dimensional Real-data MPI Transforms (FFTW 3.3.10)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Other Multi-dimensional Real-data MPI Transforms (FFTW 3.3.10)">
|
||
|
|
<meta name="keywords" content="Other Multi-dimensional Real-data MPI Transforms (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="Distributed_002dmemory-FFTW-with-MPI.html" rel="up" title="Distributed-memory FFTW with MPI">
|
||
|
|
<link href="FFTW-MPI-Transposes.html" rel="next" title="FFTW MPI Transposes">
|
||
|
|
<link href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html" rel="prev" title="Multi-dimensional MPI DFTs of Real Data">
|
||
|
|
<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="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms"></span><div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="FFTW-MPI-Transposes.html" accesskey="n" rel="next">FFTW MPI Transposes</a>, Previous: <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html" accesskey="p" rel="prev">Multi-dimensional MPI DFTs of Real Data</a>, Up: <a href="Distributed_002dmemory-FFTW-with-MPI.html" accesskey="u" rel="up">Distributed-memory FFTW with MPI</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="Other-multi_002ddimensional-Real_002dData-MPI-Transforms"></span><h3 class="section">6.6 Other multi-dimensional Real-Data MPI Transforms</h3>
|
||
|
|
|
||
|
|
<span id="index-r2r-3"></span>
|
||
|
|
<p>FFTW’s MPI interface also supports multi-dimensional ‘<samp>r2r</samp>’
|
||
|
|
transforms of all kinds supported by the serial interface
|
||
|
|
(e.g. discrete cosine and sine transforms, discrete Hartley
|
||
|
|
transforms, etc.). Only multi-dimensional ‘<samp>r2r</samp>’ transforms, not
|
||
|
|
one-dimensional transforms, are currently parallelized.
|
||
|
|
</p>
|
||
|
|
<span id="index-fftw_005fr2r_005fkind-1"></span>
|
||
|
|
<p>These are used much like the multidimensional complex DFTs discussed
|
||
|
|
above, except that the data is real rather than complex, and one needs
|
||
|
|
to pass an r2r transform kind (<code>fftw_r2r_kind</code>) for each
|
||
|
|
dimension as in the serial FFTW (see <a href="More-DFTs-of-Real-Data.html">More DFTs of Real Data</a>).
|
||
|
|
</p>
|
||
|
|
<p>For example, one might perform a two-dimensional L × M
|
||
|
|
that is
|
||
|
|
an REDFT10 (DCT-II) in the first dimension and an RODFT10 (DST-II) in
|
||
|
|
the second dimension with code like:
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example"> const ptrdiff_t L = ..., M = ...;
|
||
|
|
fftw_plan plan;
|
||
|
|
double *data;
|
||
|
|
ptrdiff_t alloc_local, local_n0, local_0_start, i, j;
|
||
|
|
|
||
|
|
/* <span class="roman">get local data size and allocate</span> */
|
||
|
|
alloc_local = fftw_mpi_local_size_2d(L, M, MPI_COMM_WORLD,
|
||
|
|
&local_n0, &local_0_start);
|
||
|
|
data = fftw_alloc_real(alloc_local);
|
||
|
|
|
||
|
|
/* <span class="roman">create plan for in-place REDFT10 x RODFT10</span> */
|
||
|
|
plan = fftw_mpi_plan_r2r_2d(L, M, data, data, MPI_COMM_WORLD,
|
||
|
|
FFTW_REDFT10, FFTW_RODFT10, FFTW_MEASURE);
|
||
|
|
|
||
|
|
/* <span class="roman">initialize data to some function</span> my_function(x,y) */
|
||
|
|
for (i = 0; i < local_n0; ++i) for (j = 0; j < M; ++j)
|
||
|
|
data[i*M + j] = my_function(local_0_start + i, j);
|
||
|
|
|
||
|
|
/* <span class="roman">compute transforms, in-place, as many times as desired</span> */
|
||
|
|
fftw_execute(plan);
|
||
|
|
|
||
|
|
fftw_destroy_plan(plan);
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<span id="index-fftw_005falloc_005freal-3"></span>
|
||
|
|
<p>Notice that we use the same ‘<samp>local_size</samp>’ functions as we did for
|
||
|
|
complex data, only now we interpret the sizes in terms of real rather
|
||
|
|
than complex values, and correspondingly use <code>fftw_alloc_real</code>.
|
||
|
|
</p>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|