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Current fftw source
| author | Chris Cannam |
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| date | Tue, 18 Oct 2016 13:40:26 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.5/doc/html/MPI-Data-Distribution-Functions.html Tue Oct 18 13:40:26 2016 +0100 @@ -0,0 +1,197 @@ +<!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 3.3.5, 30 July 2016). + +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 5.2, http://www.gnu.org/software/texinfo/ --> +<head> +<title>FFTW 3.3.5: MPI Data Distribution Functions</title> + +<meta name="description" content="FFTW 3.3.5: MPI Data Distribution Functions"> +<meta name="keywords" content="FFTW 3.3.5: MPI Data Distribution Functions"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" rel="up" title="FFTW MPI Reference"> +<link href="MPI-Plan-Creation.html#MPI-Plan-Creation" rel="next" title="MPI Plan Creation"> +<link href="Using-MPI-Plans.html#Using-MPI-Plans" rel="prev" title="Using MPI Plans"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {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} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="MPI-Data-Distribution-Functions"></a> +<div class="header"> +<p> +Next: <a href="MPI-Plan-Creation.html#MPI-Plan-Creation" accesskey="n" rel="next">MPI Plan Creation</a>, Previous: <a href="Using-MPI-Plans.html#Using-MPI-Plans" accesskey="p" rel="prev">Using MPI Plans</a>, Up: <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" accesskey="u" rel="up">FFTW MPI Reference</a> [<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> +</div> +<hr> +<a name="MPI-Data-Distribution-Functions-1"></a> +<h4 class="subsection">6.12.4 MPI Data Distribution Functions</h4> + +<a name="index-data-distribution-5"></a> +<p>As described above (see <a href="MPI-Data-Distribution.html#MPI-Data-Distribution">MPI Data Distribution</a>), in order to +allocate your arrays, <em>before</em> creating a plan, you must first +call one of the following routines to determine the required +allocation size and the portion of the array locally stored on a given +process. The <code>MPI_Comm</code> communicator passed here must be +equivalent to the communicator used below for plan creation. +</p> +<p>The basic interface for multidimensional transforms consists of the +functions: +</p> +<a name="index-fftw_005fmpi_005flocal_005fsize_005f2d-2"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005f3d"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005f2d_005ftransposed-1"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005f3d_005ftransposed-1"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005ftransposed"></a> +<div class="example"> +<pre class="example">ptrdiff_t fftw_mpi_local_size_2d(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start); +ptrdiff_t fftw_mpi_local_size_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2, + MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start); +ptrdiff_t fftw_mpi_local_size(int rnk, const ptrdiff_t *n, MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start); + +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); +ptrdiff_t fftw_mpi_local_size_3d_transposed(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2, + MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start, + ptrdiff_t *local_n1, ptrdiff_t *local_1_start); +ptrdiff_t fftw_mpi_local_size_transposed(int rnk, const ptrdiff_t *n, MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start, + ptrdiff_t *local_n1, ptrdiff_t *local_1_start); +</pre></div> + +<p>These functions return the number of elements to allocate (complex +numbers for DFT/r2c/c2r plans, real numbers for r2r plans), whereas +the <code>local_n0</code> and <code>local_0_start</code> return the portion +(<code>local_0_start</code> to <code>local_0_start + local_n0 - 1</code>) of the +first dimension of an n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × n<sub>d-1</sub> array that is stored on the local +process. See <a href="Basic-and-advanced-distribution-interfaces.html#Basic-and-advanced-distribution-interfaces">Basic and advanced distribution interfaces</a>. For +<code>FFTW_MPI_TRANSPOSED_OUT</code> plans, the ‘<samp>_transposed</samp>’ variants +are useful in order to also return the local portion of the first +dimension in the n<sub>1</sub> × n<sub>0</sub> × n<sub>2</sub> ×…× n<sub>d-1</sub> transposed output. +See <a href="Transposed-distributions.html#Transposed-distributions">Transposed distributions</a>. +The advanced interface for multidimensional transforms is: +</p> +<a name="index-advanced-interface-5"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005fmany-1"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed-1"></a> +<div class="example"> +<pre class="example">ptrdiff_t fftw_mpi_local_size_many(int rnk, const ptrdiff_t *n, ptrdiff_t howmany, + ptrdiff_t block0, MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start); +ptrdiff_t fftw_mpi_local_size_many_transposed(int rnk, const ptrdiff_t *n, ptrdiff_t howmany, + ptrdiff_t block0, ptrdiff_t block1, MPI_Comm comm, + ptrdiff_t *local_n0, ptrdiff_t *local_0_start, + ptrdiff_t *local_n1, ptrdiff_t *local_1_start); +</pre></div> + +<p>These differ from the basic interface in only two ways. First, they +allow you to specify block sizes <code>block0</code> and <code>block1</code> (the +latter for the transposed output); you can pass +<code>FFTW_MPI_DEFAULT_BLOCK</code> to use FFTW’s default block size as in +the basic interface. Second, you can pass a <code>howmany</code> parameter, +corresponding to the advanced planning interface below: this is for +transforms of contiguous <code>howmany</code>-tuples of numbers +(<code>howmany = 1</code> in the basic interface). +</p> +<p>The corresponding basic and advanced routines for one-dimensional +transforms (currently only complex DFTs) are: +</p> +<a name="index-fftw_005fmpi_005flocal_005fsize_005f1d-1"></a> +<a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005f1d"></a> +<div class="example"> +<pre class="example">ptrdiff_t fftw_mpi_local_size_1d( + ptrdiff_t n0, MPI_Comm comm, int sign, unsigned flags, + ptrdiff_t *local_ni, ptrdiff_t *local_i_start, + ptrdiff_t *local_no, ptrdiff_t *local_o_start); +ptrdiff_t fftw_mpi_local_size_many_1d( + ptrdiff_t n0, ptrdiff_t howmany, + MPI_Comm comm, int sign, unsigned flags, + ptrdiff_t *local_ni, ptrdiff_t *local_i_start, + ptrdiff_t *local_no, ptrdiff_t *local_o_start); +</pre></div> + +<a name="index-FFTW_005fMPI_005fSCRAMBLED_005fOUT-1"></a> +<a name="index-FFTW_005fMPI_005fSCRAMBLED_005fIN-1"></a> +<p>As above, the return value is the number of elements to allocate +(complex numbers, for complex DFTs). The <code>local_ni</code> and +<code>local_i_start</code> arguments return the portion +(<code>local_i_start</code> to <code>local_i_start + local_ni - 1</code>) of the +1d array that is stored on this process for the transform +<em>input</em>, and <code>local_no</code> and <code>local_o_start</code> are the +corresponding quantities for the input. The <code>sign</code> +(<code>FFTW_FORWARD</code> or <code>FFTW_BACKWARD</code>) and <code>flags</code> must +match the arguments passed when creating a plan. Although the inputs +and outputs have different data distributions in general, it is +guaranteed that the <em>output</em> data distribution of an +<code>FFTW_FORWARD</code> plan will match the <em>input</em> data distribution +of an <code>FFTW_BACKWARD</code> plan and vice versa; similarly for the +<code>FFTW_MPI_SCRAMBLED_OUT</code> and <code>FFTW_MPI_SCRAMBLED_IN</code> flags. +See <a href="One_002ddimensional-distributions.html#One_002ddimensional-distributions">One-dimensional distributions</a>. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="MPI-Plan-Creation.html#MPI-Plan-Creation" accesskey="n" rel="next">MPI Plan Creation</a>, Previous: <a href="Using-MPI-Plans.html#Using-MPI-Plans" accesskey="p" rel="prev">Using MPI Plans</a>, Up: <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" accesskey="u" rel="up">FFTW MPI Reference</a> [<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> +</div> + + + +</body> +</html>