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			98 lines
		
	
	
		
			4.7 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
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|  | <span id="Advanced-distributed_002dtranspose-interface-1"></span><h4 class="subsection">6.7.2 Advanced distributed-transpose interface</h4> | ||
|  | 
 | ||
|  | <p>The above routines are for a transpose of a matrix of numbers (of type | ||
|  | <code>double</code>), using FFTW’s default block sizes.  More generally, one | ||
|  | can perform transposes of <em>tuples</em> of numbers, with | ||
|  | user-specified block sizes for the input and output: | ||
|  | </p> | ||
|  | <div class="example"> | ||
|  | <pre class="example">fftw_plan fftw_mpi_plan_many_transpose | ||
|  |                 (ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t howmany, | ||
|  |                  ptrdiff_t block0, ptrdiff_t block1, | ||
|  |                  double *in, double *out, MPI_Comm comm, unsigned flags); | ||
|  | </pre></div> | ||
|  | <span id="index-fftw_005fmpi_005fplan_005fmany_005ftranspose"></span> | ||
|  | 
 | ||
|  | <p>In this case, one is transposing an <code>n0</code> by <code>n1</code> matrix of | ||
|  | <code>howmany</code>-tuples (e.g. <code>howmany = 2</code> for complex numbers). | ||
|  | The input is distributed along the <code>n0</code> dimension with block size | ||
|  | <code>block0</code>, and the <code>n1</code> by <code>n0</code> output is distributed | ||
|  | along the <code>n1</code> dimension with block size <code>block1</code>.  If | ||
|  | <code>FFTW_MPI_DEFAULT_BLOCK</code> (0) is passed for a block size then FFTW | ||
|  | uses its default block size.  To get the local size of the data on | ||
|  | each process, you should then call <code>fftw_mpi_local_size_many_transposed</code>. | ||
|  | <span id="index-FFTW_005fMPI_005fDEFAULT_005fBLOCK-1"></span> | ||
|  | <span id="index-fftw_005fmpi_005flocal_005fsize_005fmany_005ftransposed"></span> | ||
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