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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 d0c2a83c1364
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Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: MPI Data Distribution Functions</title>
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Chris@82 68 </head>
Chris@82 69
Chris@82 70 <body lang="en">
Chris@82 71 <a name="MPI-Data-Distribution-Functions"></a>
Chris@82 72 <div class="header">
Chris@82 73 <p>
Chris@82 74 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@82 75 </div>
Chris@82 76 <hr>
Chris@82 77 <a name="MPI-Data-Distribution-Functions-1"></a>
Chris@82 78 <h4 class="subsection">6.12.4 MPI Data Distribution Functions</h4>
Chris@82 79
Chris@82 80 <a name="index-data-distribution-5"></a>
Chris@82 81 <p>As described above (see <a href="MPI-Data-Distribution.html#MPI-Data-Distribution">MPI Data Distribution</a>), in order to
Chris@82 82 allocate your arrays, <em>before</em> creating a plan, you must first
Chris@82 83 call one of the following routines to determine the required
Chris@82 84 allocation size and the portion of the array locally stored on a given
Chris@82 85 process. The <code>MPI_Comm</code> communicator passed here must be
Chris@82 86 equivalent to the communicator used below for plan creation.
Chris@82 87 </p>
Chris@82 88 <p>The basic interface for multidimensional transforms consists of the
Chris@82 89 functions:
Chris@82 90 </p>
Chris@82 91 <a name="index-fftw_005fmpi_005flocal_005fsize_005f2d-2"></a>
Chris@82 92 <a name="index-fftw_005fmpi_005flocal_005fsize_005f3d"></a>
Chris@82 93 <a name="index-fftw_005fmpi_005flocal_005fsize"></a>
Chris@82 94 <a name="index-fftw_005fmpi_005flocal_005fsize_005f2d_005ftransposed-1"></a>
Chris@82 95 <a name="index-fftw_005fmpi_005flocal_005fsize_005f3d_005ftransposed-1"></a>
Chris@82 96 <a name="index-fftw_005fmpi_005flocal_005fsize_005ftransposed"></a>
Chris@82 97 <div class="example">
Chris@82 98 <pre class="example">ptrdiff_t fftw_mpi_local_size_2d(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
Chris@82 99 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@82 100 ptrdiff_t fftw_mpi_local_size_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
Chris@82 101 MPI_Comm comm,
Chris@82 102 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@82 103 ptrdiff_t fftw_mpi_local_size(int rnk, const ptrdiff_t *n, MPI_Comm comm,
Chris@82 104 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@82 105
Chris@82 106 ptrdiff_t fftw_mpi_local_size_2d_transposed(ptrdiff_t n0, ptrdiff_t n1, MPI_Comm comm,
Chris@82 107 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@82 108 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@82 109 ptrdiff_t fftw_mpi_local_size_3d_transposed(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
Chris@82 110 MPI_Comm comm,
Chris@82 111 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@82 112 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@82 113 ptrdiff_t fftw_mpi_local_size_transposed(int rnk, const ptrdiff_t *n, MPI_Comm comm,
Chris@82 114 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@82 115 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@82 116 </pre></div>
Chris@82 117
Chris@82 118 <p>These functions return the number of elements to allocate (complex
Chris@82 119 numbers for DFT/r2c/c2r plans, real numbers for r2r plans), whereas
Chris@82 120 the <code>local_n0</code> and <code>local_0_start</code> return the portion
Chris@82 121 (<code>local_0_start</code> to <code>local_0_start + local_n0 - 1</code>) of the
Chris@82 122 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>
Chris@82 123 array that is stored on the local
Chris@82 124 process. See <a href="Basic-and-advanced-distribution-interfaces.html#Basic-and-advanced-distribution-interfaces">Basic and advanced distribution interfaces</a>. For
Chris@82 125 <code>FFTW_MPI_TRANSPOSED_OUT</code> plans, the &lsquo;<samp>_transposed</samp>&rsquo; variants
Chris@82 126 are useful in order to also return the local portion of the first
Chris@82 127 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>
Chris@82 128 transposed output.
Chris@82 129 See <a href="Transposed-distributions.html#Transposed-distributions">Transposed distributions</a>.
Chris@82 130 The advanced interface for multidimensional transforms is:
Chris@82 131 </p>
Chris@82 132 <a name="index-advanced-interface-5"></a>
Chris@82 133 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany-1"></a>
Chris@82 134 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed-1"></a>
Chris@82 135 <div class="example">
Chris@82 136 <pre class="example">ptrdiff_t fftw_mpi_local_size_many(int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
Chris@82 137 ptrdiff_t block0, MPI_Comm comm,
Chris@82 138 ptrdiff_t *local_n0, ptrdiff_t *local_0_start);
Chris@82 139 ptrdiff_t fftw_mpi_local_size_many_transposed(int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
Chris@82 140 ptrdiff_t block0, ptrdiff_t block1, MPI_Comm comm,
Chris@82 141 ptrdiff_t *local_n0, ptrdiff_t *local_0_start,
Chris@82 142 ptrdiff_t *local_n1, ptrdiff_t *local_1_start);
Chris@82 143 </pre></div>
Chris@82 144
Chris@82 145 <p>These differ from the basic interface in only two ways. First, they
Chris@82 146 allow you to specify block sizes <code>block0</code> and <code>block1</code> (the
Chris@82 147 latter for the transposed output); you can pass
Chris@82 148 <code>FFTW_MPI_DEFAULT_BLOCK</code> to use FFTW&rsquo;s default block size as in
Chris@82 149 the basic interface. Second, you can pass a <code>howmany</code> parameter,
Chris@82 150 corresponding to the advanced planning interface below: this is for
Chris@82 151 transforms of contiguous <code>howmany</code>-tuples of numbers
Chris@82 152 (<code>howmany = 1</code> in the basic interface).
Chris@82 153 </p>
Chris@82 154 <p>The corresponding basic and advanced routines for one-dimensional
Chris@82 155 transforms (currently only complex DFTs) are:
Chris@82 156 </p>
Chris@82 157 <a name="index-fftw_005fmpi_005flocal_005fsize_005f1d-1"></a>
Chris@82 158 <a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005f1d"></a>
Chris@82 159 <div class="example">
Chris@82 160 <pre class="example">ptrdiff_t fftw_mpi_local_size_1d(
Chris@82 161 ptrdiff_t n0, MPI_Comm comm, int sign, unsigned flags,
Chris@82 162 ptrdiff_t *local_ni, ptrdiff_t *local_i_start,
Chris@82 163 ptrdiff_t *local_no, ptrdiff_t *local_o_start);
Chris@82 164 ptrdiff_t fftw_mpi_local_size_many_1d(
Chris@82 165 ptrdiff_t n0, ptrdiff_t howmany,
Chris@82 166 MPI_Comm comm, int sign, unsigned flags,
Chris@82 167 ptrdiff_t *local_ni, ptrdiff_t *local_i_start,
Chris@82 168 ptrdiff_t *local_no, ptrdiff_t *local_o_start);
Chris@82 169 </pre></div>
Chris@82 170
Chris@82 171 <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fOUT-1"></a>
Chris@82 172 <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fIN-1"></a>
Chris@82 173 <p>As above, the return value is the number of elements to allocate
Chris@82 174 (complex numbers, for complex DFTs). The <code>local_ni</code> and
Chris@82 175 <code>local_i_start</code> arguments return the portion
Chris@82 176 (<code>local_i_start</code> to <code>local_i_start + local_ni - 1</code>) of the
Chris@82 177 1d array that is stored on this process for the transform
Chris@82 178 <em>input</em>, and <code>local_no</code> and <code>local_o_start</code> are the
Chris@82 179 corresponding quantities for the input. The <code>sign</code>
Chris@82 180 (<code>FFTW_FORWARD</code> or <code>FFTW_BACKWARD</code>) and <code>flags</code> must
Chris@82 181 match the arguments passed when creating a plan. Although the inputs
Chris@82 182 and outputs have different data distributions in general, it is
Chris@82 183 guaranteed that the <em>output</em> data distribution of an
Chris@82 184 <code>FFTW_FORWARD</code> plan will match the <em>input</em> data distribution
Chris@82 185 of an <code>FFTW_BACKWARD</code> plan and vice versa; similarly for the
Chris@82 186 <code>FFTW_MPI_SCRAMBLED_OUT</code> and <code>FFTW_MPI_SCRAMBLED_IN</code> flags.
Chris@82 187 See <a href="One_002ddimensional-distributions.html#One_002ddimensional-distributions">One-dimensional distributions</a>.
Chris@82 188 </p>
Chris@82 189 <hr>
Chris@82 190 <div class="header">
Chris@82 191 <p>
Chris@82 192 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@82 193 </div>
Chris@82 194
Chris@82 195
Chris@82 196
Chris@82 197 </body>
Chris@82 198 </html>