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Add FFTW 3.3.8 source, and a Linux build
author Chris Cannam
date Tue, 19 Nov 2019 14:52:55 +0000
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Chris@82 24 <head>
Chris@82 25 <title>FFTW 3.3.8: MPI Data Distribution Functions</title>
Chris@82 26
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Chris@82 37 <link href="MPI-Plan-Creation.html#MPI-Plan-Creation" rel="next" title="MPI Plan Creation">
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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
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Chris@82 198 </html>