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author Chris Cannam
date Wed, 20 Mar 2013 15:35:50 +0000
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Chris@10 49 <a name="Advanced-distributed-transpose-interface"></a>
Chris@10 50 <a name="Advanced-distributed_002dtranspose-interface"></a>
Chris@10 51 <p>
Chris@10 52 Next:&nbsp;<a rel="next" accesskey="n" href="An-improved-replacement-for-MPI_005fAlltoall.html#An-improved-replacement-for-MPI_005fAlltoall">An improved replacement for MPI_Alltoall</a>,
Chris@10 53 Previous:&nbsp;<a rel="previous" accesskey="p" href="Basic-distributed_002dtranspose-interface.html#Basic-distributed_002dtranspose-interface">Basic distributed-transpose interface</a>,
Chris@10 54 Up:&nbsp;<a rel="up" accesskey="u" href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes">FFTW MPI Transposes</a>
Chris@10 55 <hr>
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Chris@10 57
Chris@10 58 <h4 class="subsection">6.7.2 Advanced distributed-transpose interface</h4>
Chris@10 59
Chris@10 60 <p>The above routines are for a transpose of a matrix of numbers (of type
Chris@10 61 <code>double</code>), using FFTW's default block sizes. More generally, one
Chris@10 62 can perform transposes of <em>tuples</em> of numbers, with
Chris@10 63 user-specified block sizes for the input and output:
Chris@10 64
Chris@10 65 <pre class="example"> fftw_plan fftw_mpi_plan_many_transpose
Chris@10 66 (ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t howmany,
Chris@10 67 ptrdiff_t block0, ptrdiff_t block1,
Chris@10 68 double *in, double *out, MPI_Comm comm, unsigned flags);
Chris@10 69 </pre>
Chris@10 70 <p><a name="index-fftw_005fmpi_005fplan_005fmany_005ftranspose-403"></a>
Chris@10 71 In this case, one is transposing an <code>n0</code> by <code>n1</code> matrix of
Chris@10 72 <code>howmany</code>-tuples (e.g. <code>howmany = 2</code> for complex numbers).
Chris@10 73 The input is distributed along the <code>n0</code> dimension with block size
Chris@10 74 <code>block0</code>, and the <code>n1</code> by <code>n0</code> output is distributed
Chris@10 75 along the <code>n1</code> dimension with block size <code>block1</code>. If
Chris@10 76 <code>FFTW_MPI_DEFAULT_BLOCK</code> (0) is passed for a block size then FFTW
Chris@10 77 uses its default block size. To get the local size of the data on
Chris@10 78 each process, you should then call <code>fftw_mpi_local_size_many_transposed</code>.
Chris@10 79 <a name="index-FFTW_005fMPI_005fDEFAULT_005fBLOCK-404"></a><a name="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed-405"></a>
Chris@10 80
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