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Current fftw source
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 18 Oct 2016 13:40:26 +0100
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cannam@127 25 <title>FFTW 3.3.5: MPI Plan Creation</title>
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cannam@127 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
cannam@127 72 <a name="MPI-Plan-Creation"></a>
cannam@127 73 <div class="header">
cannam@127 74 <p>
cannam@127 75 Next: <a href="MPI-Wisdom-Communication.html#MPI-Wisdom-Communication" accesskey="n" rel="next">MPI Wisdom Communication</a>, Previous: <a href="MPI-Data-Distribution-Functions.html#MPI-Data-Distribution-Functions" accesskey="p" rel="prev">MPI Data Distribution Functions</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>
cannam@127 76 </div>
cannam@127 77 <hr>
cannam@127 78 <a name="MPI-Plan-Creation-1"></a>
cannam@127 79 <h4 class="subsection">6.12.5 MPI Plan Creation</h4>
cannam@127 80
cannam@127 81 <a name="Complex_002ddata-MPI-DFTs"></a>
cannam@127 82 <h4 class="subsubheading">Complex-data MPI DFTs</h4>
cannam@127 83
cannam@127 84 <p>Plans for complex-data DFTs (see <a href="2d-MPI-example.html#g_t2d-MPI-example">2d MPI example</a>) are created by:
cannam@127 85 </p>
cannam@127 86 <a name="index-fftw_005fmpi_005fplan_005fdft_005f1d"></a>
cannam@127 87 <a name="index-fftw_005fmpi_005fplan_005fdft_005f2d-1"></a>
cannam@127 88 <a name="index-fftw_005fmpi_005fplan_005fdft_005f3d"></a>
cannam@127 89 <a name="index-fftw_005fmpi_005fplan_005fdft"></a>
cannam@127 90 <a name="index-fftw_005fmpi_005fplan_005fmany_005fdft"></a>
cannam@127 91 <div class="example">
cannam@127 92 <pre class="example">fftw_plan fftw_mpi_plan_dft_1d(ptrdiff_t n0, fftw_complex *in, fftw_complex *out,
cannam@127 93 MPI_Comm comm, int sign, unsigned flags);
cannam@127 94 fftw_plan fftw_mpi_plan_dft_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 95 fftw_complex *in, fftw_complex *out,
cannam@127 96 MPI_Comm comm, int sign, unsigned flags);
cannam@127 97 fftw_plan fftw_mpi_plan_dft_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
cannam@127 98 fftw_complex *in, fftw_complex *out,
cannam@127 99 MPI_Comm comm, int sign, unsigned flags);
cannam@127 100 fftw_plan fftw_mpi_plan_dft(int rnk, const ptrdiff_t *n,
cannam@127 101 fftw_complex *in, fftw_complex *out,
cannam@127 102 MPI_Comm comm, int sign, unsigned flags);
cannam@127 103 fftw_plan fftw_mpi_plan_many_dft(int rnk, const ptrdiff_t *n,
cannam@127 104 ptrdiff_t howmany, ptrdiff_t block, ptrdiff_t tblock,
cannam@127 105 fftw_complex *in, fftw_complex *out,
cannam@127 106 MPI_Comm comm, int sign, unsigned flags);
cannam@127 107 </pre></div>
cannam@127 108
cannam@127 109 <a name="index-MPI-communicator-2"></a>
cannam@127 110 <a name="index-collective-function-4"></a>
cannam@127 111 <p>These are similar to their serial counterparts (see <a href="Complex-DFTs.html#Complex-DFTs">Complex DFTs</a>)
cannam@127 112 in specifying the dimensions, sign, and flags of the transform. The
cannam@127 113 <code>comm</code> argument gives an MPI communicator that specifies the set
cannam@127 114 of processes to participate in the transform; plan creation is a
cannam@127 115 collective function that must be called for all processes in the
cannam@127 116 communicator. The <code>in</code> and <code>out</code> pointers refer only to a
cannam@127 117 portion of the overall transform data (see <a href="MPI-Data-Distribution.html#MPI-Data-Distribution">MPI Data Distribution</a>)
cannam@127 118 as specified by the &lsquo;<samp>local_size</samp>&rsquo; functions in the previous
cannam@127 119 section. Unless <code>flags</code> contains <code>FFTW_ESTIMATE</code>, these
cannam@127 120 arrays are overwritten during plan creation as for the serial
cannam@127 121 interface. For multi-dimensional transforms, any dimensions <code>&gt;
cannam@127 122 1</code> are supported; for one-dimensional transforms, only composite
cannam@127 123 (non-prime) <code>n0</code> are currently supported (unlike the serial
cannam@127 124 FFTW). Requesting an unsupported transform size will yield a
cannam@127 125 <code>NULL</code> plan. (As in the serial interface, highly composite sizes
cannam@127 126 generally yield the best performance.)
cannam@127 127 </p>
cannam@127 128 <a name="index-advanced-interface-6"></a>
cannam@127 129 <a name="index-FFTW_005fMPI_005fDEFAULT_005fBLOCK-2"></a>
cannam@127 130 <a name="index-stride-3"></a>
cannam@127 131 <p>The advanced-interface <code>fftw_mpi_plan_many_dft</code> additionally
cannam@127 132 allows you to specify the block sizes for the first dimension
cannam@127 133 (<code>block</code>) of the 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> input data and the first dimension
cannam@127 134 (<code>tblock</code>) of 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 data (at intermediate
cannam@127 135 steps of the transform, and for the output if
cannam@127 136 <code>FFTW_TRANSPOSED_OUT</code> is specified in <code>flags</code>). These must
cannam@127 137 be the same block sizes as were passed to the corresponding
cannam@127 138 &lsquo;<samp>local_size</samp>&rsquo; function; you can pass <code>FFTW_MPI_DEFAULT_BLOCK</code>
cannam@127 139 to use FFTW&rsquo;s default block size as in the basic interface. Also, the
cannam@127 140 <code>howmany</code> parameter specifies that the transform is of contiguous
cannam@127 141 <code>howmany</code>-tuples rather than individual complex numbers; this
cannam@127 142 corresponds to the same parameter in the serial advanced interface
cannam@127 143 (see <a href="Advanced-Complex-DFTs.html#Advanced-Complex-DFTs">Advanced Complex DFTs</a>) with <code>stride = howmany</code> and
cannam@127 144 <code>dist = 1</code>.
cannam@127 145 </p>
cannam@127 146 <a name="MPI-flags"></a>
cannam@127 147 <h4 class="subsubheading">MPI flags</h4>
cannam@127 148
cannam@127 149 <p>The <code>flags</code> can be any of those for the serial FFTW
cannam@127 150 (see <a href="Planner-Flags.html#Planner-Flags">Planner Flags</a>), and in addition may include one or more of
cannam@127 151 the following MPI-specific flags, which improve performance at the
cannam@127 152 cost of changing the output or input data formats.
cannam@127 153 </p>
cannam@127 154 <ul>
cannam@127 155 <li> <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fOUT-2"></a>
cannam@127 156 <a name="index-FFTW_005fMPI_005fSCRAMBLED_005fIN-2"></a>
cannam@127 157 <code>FFTW_MPI_SCRAMBLED_OUT</code>, <code>FFTW_MPI_SCRAMBLED_IN</code>: valid for
cannam@127 158 1d transforms only, these flags indicate that the output/input of the
cannam@127 159 transform are in an undocumented &ldquo;scrambled&rdquo; order. A forward
cannam@127 160 <code>FFTW_MPI_SCRAMBLED_OUT</code> transform can be inverted by a backward
cannam@127 161 <code>FFTW_MPI_SCRAMBLED_IN</code> (times the usual 1/<i>N</i> normalization).
cannam@127 162 See <a href="One_002ddimensional-distributions.html#One_002ddimensional-distributions">One-dimensional distributions</a>.
cannam@127 163
cannam@127 164 </li><li> <a name="index-FFTW_005fMPI_005fTRANSPOSED_005fOUT-2"></a>
cannam@127 165 <a name="index-FFTW_005fMPI_005fTRANSPOSED_005fIN-2"></a>
cannam@127 166 <code>FFTW_MPI_TRANSPOSED_OUT</code>, <code>FFTW_MPI_TRANSPOSED_IN</code>: valid
cannam@127 167 for multidimensional (<code>rnk &gt; 1</code>) transforms only, these flags
cannam@127 168 specify that the output or input 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> transform is
cannam@127 169 transposed to 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>. See <a href="Transposed-distributions.html#Transposed-distributions">Transposed distributions</a>.
cannam@127 170
cannam@127 171 </li></ul>
cannam@127 172
cannam@127 173 <a name="Real_002ddata-MPI-DFTs"></a>
cannam@127 174 <h4 class="subsubheading">Real-data MPI DFTs</h4>
cannam@127 175
cannam@127 176 <a name="index-r2c-4"></a>
cannam@127 177 <p>Plans for real-input/output (r2c/c2r) DFTs (see <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data">Multi-dimensional MPI DFTs of Real Data</a>) are created by:
cannam@127 178 </p>
cannam@127 179 <a name="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f2d"></a>
cannam@127 180 <a name="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f2d-1"></a>
cannam@127 181 <a name="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f3d"></a>
cannam@127 182 <a name="index-fftw_005fmpi_005fplan_005fdft_005fr2c"></a>
cannam@127 183 <a name="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f2d"></a>
cannam@127 184 <a name="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f2d-1"></a>
cannam@127 185 <a name="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f3d"></a>
cannam@127 186 <a name="index-fftw_005fmpi_005fplan_005fdft_005fc2r"></a>
cannam@127 187 <div class="example">
cannam@127 188 <pre class="example">fftw_plan fftw_mpi_plan_dft_r2c_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 189 double *in, fftw_complex *out,
cannam@127 190 MPI_Comm comm, unsigned flags);
cannam@127 191 fftw_plan fftw_mpi_plan_dft_r2c_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 192 double *in, fftw_complex *out,
cannam@127 193 MPI_Comm comm, unsigned flags);
cannam@127 194 fftw_plan fftw_mpi_plan_dft_r2c_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
cannam@127 195 double *in, fftw_complex *out,
cannam@127 196 MPI_Comm comm, unsigned flags);
cannam@127 197 fftw_plan fftw_mpi_plan_dft_r2c(int rnk, const ptrdiff_t *n,
cannam@127 198 double *in, fftw_complex *out,
cannam@127 199 MPI_Comm comm, unsigned flags);
cannam@127 200 fftw_plan fftw_mpi_plan_dft_c2r_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 201 fftw_complex *in, double *out,
cannam@127 202 MPI_Comm comm, unsigned flags);
cannam@127 203 fftw_plan fftw_mpi_plan_dft_c2r_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 204 fftw_complex *in, double *out,
cannam@127 205 MPI_Comm comm, unsigned flags);
cannam@127 206 fftw_plan fftw_mpi_plan_dft_c2r_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
cannam@127 207 fftw_complex *in, double *out,
cannam@127 208 MPI_Comm comm, unsigned flags);
cannam@127 209 fftw_plan fftw_mpi_plan_dft_c2r(int rnk, const ptrdiff_t *n,
cannam@127 210 fftw_complex *in, double *out,
cannam@127 211 MPI_Comm comm, unsigned flags);
cannam@127 212 </pre></div>
cannam@127 213
cannam@127 214 <p>Similar to the serial interface (see <a href="Real_002ddata-DFTs.html#Real_002ddata-DFTs">Real-data DFTs</a>), these
cannam@127 215 transform logically 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> real data to/from 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>/2 + 1) complex
cannam@127 216 data, representing the non-redundant half of the conjugate-symmetry
cannam@127 217 output of a real-input DFT (see <a href="Multi_002ddimensional-Transforms.html#Multi_002ddimensional-Transforms">Multi-dimensional Transforms</a>).
cannam@127 218 However, the real array must be stored within a padded 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;[2&nbsp;(n<sub>d-1</sub>/2 + 1)]
cannam@127 219 array (much like the in-place serial r2c transforms, but here for
cannam@127 220 out-of-place transforms as well). Currently, only multi-dimensional
cannam@127 221 (<code>rnk &gt; 1</code>) r2c/c2r transforms are supported (requesting a plan
cannam@127 222 for <code>rnk = 1</code> will yield <code>NULL</code>). As explained above
cannam@127 223 (see <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data">Multi-dimensional MPI DFTs of Real Data</a>), the data
cannam@127 224 distribution of both the real and complex arrays is given by the
cannam@127 225 &lsquo;<samp>local_size</samp>&rsquo; function called for the dimensions of the
cannam@127 226 <em>complex</em> array. Similar to the other planning functions, the
cannam@127 227 input and output arrays are overwritten when the plan is created
cannam@127 228 except in <code>FFTW_ESTIMATE</code> mode.
cannam@127 229 </p>
cannam@127 230 <p>As for the complex DFTs above, there is an advance interface that
cannam@127 231 allows you to manually specify block sizes and to transform contiguous
cannam@127 232 <code>howmany</code>-tuples of real/complex numbers:
cannam@127 233 </p>
cannam@127 234 <a name="index-fftw_005fmpi_005fplan_005fmany_005fdft_005fr2c"></a>
cannam@127 235 <a name="index-fftw_005fmpi_005fplan_005fmany_005fdft_005fc2r"></a>
cannam@127 236 <div class="example">
cannam@127 237 <pre class="example">fftw_plan fftw_mpi_plan_many_dft_r2c
cannam@127 238 (int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
cannam@127 239 ptrdiff_t iblock, ptrdiff_t oblock,
cannam@127 240 double *in, fftw_complex *out,
cannam@127 241 MPI_Comm comm, unsigned flags);
cannam@127 242 fftw_plan fftw_mpi_plan_many_dft_c2r
cannam@127 243 (int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
cannam@127 244 ptrdiff_t iblock, ptrdiff_t oblock,
cannam@127 245 fftw_complex *in, double *out,
cannam@127 246 MPI_Comm comm, unsigned flags);
cannam@127 247 </pre></div>
cannam@127 248
cannam@127 249 <a name="MPI-r2r-transforms"></a>
cannam@127 250 <h4 class="subsubheading">MPI r2r transforms</h4>
cannam@127 251
cannam@127 252 <a name="index-r2r-4"></a>
cannam@127 253 <p>There are corresponding plan-creation routines for r2r
cannam@127 254 transforms (see <a href="More-DFTs-of-Real-Data.html#More-DFTs-of-Real-Data">More DFTs of Real Data</a>), currently supporting
cannam@127 255 multidimensional (<code>rnk &gt; 1</code>) transforms only (<code>rnk = 1</code> will
cannam@127 256 yield a <code>NULL</code> plan):
cannam@127 257 </p>
cannam@127 258 <div class="example">
cannam@127 259 <pre class="example">fftw_plan fftw_mpi_plan_r2r_2d(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 260 double *in, double *out,
cannam@127 261 MPI_Comm comm,
cannam@127 262 fftw_r2r_kind kind0, fftw_r2r_kind kind1,
cannam@127 263 unsigned flags);
cannam@127 264 fftw_plan fftw_mpi_plan_r2r_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
cannam@127 265 double *in, double *out,
cannam@127 266 MPI_Comm comm,
cannam@127 267 fftw_r2r_kind kind0, fftw_r2r_kind kind1, fftw_r2r_kind kind2,
cannam@127 268 unsigned flags);
cannam@127 269 fftw_plan fftw_mpi_plan_r2r(int rnk, const ptrdiff_t *n,
cannam@127 270 double *in, double *out,
cannam@127 271 MPI_Comm comm, const fftw_r2r_kind *kind,
cannam@127 272 unsigned flags);
cannam@127 273 fftw_plan fftw_mpi_plan_many_r2r(int rnk, const ptrdiff_t *n,
cannam@127 274 ptrdiff_t iblock, ptrdiff_t oblock,
cannam@127 275 double *in, double *out,
cannam@127 276 MPI_Comm comm, const fftw_r2r_kind *kind,
cannam@127 277 unsigned flags);
cannam@127 278 </pre></div>
cannam@127 279
cannam@127 280 <p>The parameters are much the same as for the complex DFTs above, except
cannam@127 281 that the arrays are of real numbers (and hence the outputs of the
cannam@127 282 &lsquo;<samp>local_size</samp>&rsquo; data-distribution functions should be interpreted as
cannam@127 283 counts of real rather than complex numbers). Also, the <code>kind</code>
cannam@127 284 parameters specify the r2r kinds along each dimension as for the
cannam@127 285 serial interface (see <a href="Real_002dto_002dReal-Transform-Kinds.html#Real_002dto_002dReal-Transform-Kinds">Real-to-Real Transform Kinds</a>). See <a href="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html#Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms">Other Multi-dimensional Real-data MPI Transforms</a>.
cannam@127 286 </p>
cannam@127 287 <a name="MPI-transposition"></a>
cannam@127 288 <h4 class="subsubheading">MPI transposition</h4>
cannam@127 289 <a name="index-transpose-5"></a>
cannam@127 290
cannam@127 291 <p>FFTW also provides routines to plan a transpose of a distributed
cannam@127 292 <code>n0</code> by <code>n1</code> array of real numbers, or an array of
cannam@127 293 <code>howmany</code>-tuples of real numbers with specified block sizes
cannam@127 294 (see <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes">FFTW MPI Transposes</a>):
cannam@127 295 </p>
cannam@127 296 <a name="index-fftw_005fmpi_005fplan_005ftranspose-1"></a>
cannam@127 297 <a name="index-fftw_005fmpi_005fplan_005fmany_005ftranspose-1"></a>
cannam@127 298 <div class="example">
cannam@127 299 <pre class="example">fftw_plan fftw_mpi_plan_transpose(ptrdiff_t n0, ptrdiff_t n1,
cannam@127 300 double *in, double *out,
cannam@127 301 MPI_Comm comm, unsigned flags);
cannam@127 302 fftw_plan fftw_mpi_plan_many_transpose
cannam@127 303 (ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t howmany,
cannam@127 304 ptrdiff_t block0, ptrdiff_t block1,
cannam@127 305 double *in, double *out, MPI_Comm comm, unsigned flags);
cannam@127 306 </pre></div>
cannam@127 307
cannam@127 308 <a name="index-new_002darray-execution-2"></a>
cannam@127 309 <a name="index-fftw_005fmpi_005fexecute_005fr2r-1"></a>
cannam@127 310 <p>These plans are used with the <code>fftw_mpi_execute_r2r</code> new-array
cannam@127 311 execute function (see <a href="Using-MPI-Plans.html#Using-MPI-Plans">Using MPI Plans</a>), since they count as (rank
cannam@127 312 zero) r2r plans from FFTW&rsquo;s perspective.
cannam@127 313 </p>
cannam@127 314 <hr>
cannam@127 315 <div class="header">
cannam@127 316 <p>
cannam@127 317 Next: <a href="MPI-Wisdom-Communication.html#MPI-Wisdom-Communication" accesskey="n" rel="next">MPI Wisdom Communication</a>, Previous: <a href="MPI-Data-Distribution-Functions.html#MPI-Data-Distribution-Functions" accesskey="p" rel="prev">MPI Data Distribution Functions</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>
cannam@127 318 </div>
cannam@127 319
cannam@127 320
cannam@127 321
cannam@127 322 </body>
cannam@127 323 </html>