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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
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Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: MPI Data Distribution Functions</title>
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Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="MPI-Data-Distribution-Functions"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 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> &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="MPI-Data-Distribution-Functions-1"></a>
Chris@42 79 <h4 class="subsection">6.12.4 MPI Data Distribution Functions</h4>
Chris@42 80
Chris@42 81 <a name="index-data-distribution-5"></a>
Chris@42 82 <p>As described above (see <a href="MPI-Data-Distribution.html#MPI-Data-Distribution">MPI Data Distribution</a>), in order to
Chris@42 83 allocate your arrays, <em>before</em> creating a plan, you must first
Chris@42 84 call one of the following routines to determine the required
Chris@42 85 allocation size and the portion of the array locally stored on a given
Chris@42 86 process. The <code>MPI_Comm</code> communicator passed here must be
Chris@42 87 equivalent to the communicator used below for plan creation.
Chris@42 88 </p>
Chris@42 89 <p>The basic interface for multidimensional transforms consists of the
Chris@42 90 functions:
Chris@42 91 </p>
Chris@42 92 <a name="index-fftw_005fmpi_005flocal_005fsize_005f2d-2"></a>
Chris@42 93 <a name="index-fftw_005fmpi_005flocal_005fsize_005f3d"></a>
Chris@42 94 <a name="index-fftw_005fmpi_005flocal_005fsize"></a>
Chris@42 95 <a name="index-fftw_005fmpi_005flocal_005fsize_005f2d_005ftransposed-1"></a>
Chris@42 96 <a name="index-fftw_005fmpi_005flocal_005fsize_005f3d_005ftransposed-1"></a>
Chris@42 97 <a name="index-fftw_005fmpi_005flocal_005fsize_005ftransposed"></a>
Chris@42 98 <div class="example">
Chris@42 99 <pre class="example">ptrdiff_t fftw_mpi_local_size_2d(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
Chris@42 100 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@42 101 ptrdiff_t fftw_mpi_local_size_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
Chris@42 102 MPI_Comm comm,
Chris@42 103 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@42 104 ptrdiff_t fftw_mpi_local_size(int rnk, const ptrdiff_t *n, MPI_Comm comm,
Chris@42 105 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@42 106
Chris@42 107 ptrdiff_t fftw_mpi_local_size_2d_transposed(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
Chris@42 108 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@42 109 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@42 110 ptrdiff_t fftw_mpi_local_size_3d_transposed(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
Chris@42 111 MPI_Comm comm,
Chris@42 112 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@42 113 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@42 114 ptrdiff_t fftw_mpi_local_size_transposed(int rnk, const ptrdiff_t *n, MPI_Comm comm,
Chris@42 115 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@42 116 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@42 117 </pre></div>
Chris@42 118
Chris@42 119 <p>These functions return the number of elements to allocate (complex
Chris@42 120 numbers for DFT/r2c/c2r plans, real numbers for r2r plans), whereas
Chris@42 121 the <code>local_n0</code> and <code>local_0_start</code> return the portion
Chris@42 122 (<code>local_0_start</code> to <code>local_0_start + local_n0 - 1</code>) of the
Chris@42 123 first dimension of an n<sub>0</sub>&nbsp;&times;&nbsp;n<sub>1</sub>&nbsp;&times;&nbsp;n<sub>2</sub>&nbsp;&times;&nbsp;&hellip;&nbsp;&times;&nbsp;n<sub>d-1</sub> array that is stored on the local
Chris@42 124 process. See <a href="Basic-and-advanced-distribution-interfaces.html#Basic-and-advanced-distribution-interfaces">Basic and advanced distribution interfaces</a>. For
Chris@42 125 <code>FFTW_MPI_TRANSPOSED_OUT</code> plans, the &lsquo;<samp>_transposed</samp>&rsquo; variants
Chris@42 126 are useful in order to also return the local portion of the first
Chris@42 127 dimension in the n<sub>1</sub>&nbsp;&times;&nbsp;n<sub>0</sub>&nbsp;&times;&nbsp;n<sub>2</sub>&nbsp;&times;&hellip;&times;&nbsp;n<sub>d-1</sub> transposed output.
Chris@42 128 See <a href="Transposed-distributions.html#Transposed-distributions">Transposed distributions</a>.
Chris@42 129 The advanced interface for multidimensional transforms is:
Chris@42 130 </p>
Chris@42 131 <a name="index-advanced-interface-5"></a>
Chris@42 132 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany-1"></a>
Chris@42 133 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed-1"></a>
Chris@42 134 <div class="example">
Chris@42 135 <pre class="example">ptrdiff_t fftw_mpi_local_size_many(int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
Chris@42 136 ptrdiff_t block0, MPI_Comm comm,
Chris@42 137 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@42 138 ptrdiff_t fftw_mpi_local_size_many_transposed(int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
Chris@42 139 ptrdiff_t block0, ptrdiff_t block1, MPI_Comm comm,
Chris@42 140 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@42 141 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@42 142 </pre></div>
Chris@42 143
Chris@42 144 <p>These differ from the basic interface in only two ways. First, they
Chris@42 145 allow you to specify block sizes <code>block0</code> and <code>block1</code> (the
Chris@42 146 latter for the transposed output); you can pass
Chris@42 147 <code>FFTW_MPI_DEFAULT_BLOCK</code> to use FFTW&rsquo;s default block size as in
Chris@42 148 the basic interface. Second, you can pass a <code>howmany</code> parameter,
Chris@42 149 corresponding to the advanced planning interface below: this is for
Chris@42 150 transforms of contiguous <code>howmany</code>-tuples of numbers
Chris@42 151 (<code>howmany = 1</code> in the basic interface).
Chris@42 152 </p>
Chris@42 153 <p>The corresponding basic and advanced routines for one-dimensional
Chris@42 154 transforms (currently only complex DFTs) are:
Chris@42 155 </p>
Chris@42 156 <a name="index-fftw_005fmpi_005flocal_005fsize_005f1d-1"></a>
Chris@42 157 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005f1d"></a>
Chris@42 158 <div class="example">
Chris@42 159 <pre class="example">ptrdiff_t fftw_mpi_local_size_1d(
Chris@42 160 ptrdiff_t n0, MPI_Comm comm, int sign, unsigned flags,
Chris@42 161 ptrdiff_t *local_ni, ptrdiff_t *local_i_start,
Chris@42 162 ptrdiff_t *local_no, ptrdiff_t *local_o_start);
Chris@42 163 ptrdiff_t fftw_mpi_local_size_many_1d(
Chris@42 164 ptrdiff_t n0, ptrdiff_t howmany,
Chris@42 165 MPI_Comm comm, int sign, unsigned flags,
Chris@42 166 ptrdiff_t *local_ni, ptrdiff_t *local_i_start,
Chris@42 167 ptrdiff_t *local_no, ptrdiff_t *local_o_start);
Chris@42 168 </pre></div>
Chris@42 169
Chris@42 170 <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fOUT-1"></a>
Chris@42 171 <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fIN-1"></a>
Chris@42 172 <p>As above, the return value is the number of elements to allocate
Chris@42 173 (complex numbers, for complex DFTs). The <code>local_ni</code> and
Chris@42 174 <code>local_i_start</code> arguments return the portion
Chris@42 175 (<code>local_i_start</code> to <code>local_i_start + local_ni - 1</code>) of the
Chris@42 176 1d array that is stored on this process for the transform
Chris@42 177 <em>input</em>, and <code>local_no</code> and <code>local_o_start</code> are the
Chris@42 178 corresponding quantities for the input. The <code>sign</code>
Chris@42 179 (<code>FFTW_FORWARD</code> or <code>FFTW_BACKWARD</code>) and <code>flags</code> must
Chris@42 180 match the arguments passed when creating a plan. Although the inputs
Chris@42 181 and outputs have different data distributions in general, it is
Chris@42 182 guaranteed that the <em>output</em> data distribution of an
Chris@42 183 <code>FFTW_FORWARD</code> plan will match the <em>input</em> data distribution
Chris@42 184 of an <code>FFTW_BACKWARD</code> plan and vice versa; similarly for the
Chris@42 185 <code>FFTW_MPI_SCRAMBLED_OUT</code> and <code>FFTW_MPI_SCRAMBLED_IN</code> flags.
Chris@42 186 See <a href="One_002ddimensional-distributions.html#One_002ddimensional-distributions">One-dimensional distributions</a>.
Chris@42 187 </p>
Chris@42 188 <hr>
Chris@42 189 <div class="header">
Chris@42 190 <p>
Chris@42 191 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> &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@42 192 </div>
Chris@42 193
Chris@42 194
Chris@42 195
Chris@42 196 </body>
Chris@42 197 </html>