314 lines
		
	
	
		
			18 KiB
		
	
	
	
		
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			314 lines
		
	
	
		
			18 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
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								<!-- This manual is for FFTW
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								(version 3.3.10, 10 December 2020).
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								Copyright (C) 2003 Matteo Frigo.
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								Copyright (C) 2003 Massachusetts Institute of Technology.
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								<title>MPI Plan Creation (FFTW 3.3.10)</title>
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								<meta name="description" content="MPI Plan Creation (FFTW 3.3.10)">
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								<link href="Concept-Index.html" rel="index" title="Concept Index">
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								<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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								<link href="FFTW-MPI-Reference.html" rel="up" title="FFTW MPI Reference">
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								<span id="MPI-Plan-Creation"></span><div class="header">
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								<p>
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								Next: <a href="MPI-Wisdom-Communication.html" accesskey="n" rel="next">MPI Wisdom Communication</a>, Previous: <a href="MPI-Data-Distribution-Functions.html" accesskey="p" rel="prev">MPI Data Distribution Functions</a>, Up: <a href="FFTW-MPI-Reference.html" accesskey="u" rel="up">FFTW MPI Reference</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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								</div>
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								<hr>
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								<span id="MPI-Plan-Creation-1"></span><h4 class="subsection">6.12.5 MPI Plan Creation</h4>
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								<span id="Complex_002ddata-MPI-DFTs"></span><h4 class="subsubheading">Complex-data MPI DFTs</h4>
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								<p>Plans for complex-data DFTs (see <a href="2d-MPI-example.html">2d MPI example</a>) are created by:
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								</p>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005f1d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005f2d-1"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005f3d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fmany_005fdft"></span>
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								<div class="example">
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								<pre class="example">fftw_plan fftw_mpi_plan_dft_1d(ptrdiff_t n0, fftw_complex *in, fftw_complex *out,
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								                               MPI_Comm comm, int sign, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_2d(ptrdiff_t n0, ptrdiff_t n1,
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								                               fftw_complex *in, fftw_complex *out,
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								                               MPI_Comm comm, int sign, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
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								                               fftw_complex *in, fftw_complex *out,
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								                               MPI_Comm comm, int sign, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft(int rnk, const ptrdiff_t *n, 
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								                            fftw_complex *in, fftw_complex *out,
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								                            MPI_Comm comm, int sign, unsigned flags);
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								fftw_plan fftw_mpi_plan_many_dft(int rnk, const ptrdiff_t *n,
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								                                 ptrdiff_t howmany, ptrdiff_t block, ptrdiff_t tblock,
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								                                 fftw_complex *in, fftw_complex *out,
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								                                 MPI_Comm comm, int sign, unsigned flags);
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								</pre></div>
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								<span id="index-MPI-communicator-2"></span>
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								<span id="index-collective-function-4"></span>
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								<p>These are similar to their serial counterparts (see <a href="Complex-DFTs.html">Complex DFTs</a>)
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								in specifying the dimensions, sign, and flags of the transform.  The
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								<code>comm</code> argument gives an MPI communicator that specifies the set
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								of processes to participate in the transform; plan creation is a
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								collective function that must be called for all processes in the
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								communicator.  The <code>in</code> and <code>out</code> pointers refer only to a
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								portion of the overall transform data (see <a href="MPI-Data-Distribution.html">MPI Data Distribution</a>)
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								as specified by the ‘<samp>local_size</samp>’ functions in the previous
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								section.  Unless <code>flags</code> contains <code>FFTW_ESTIMATE</code>, these
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								arrays are overwritten during plan creation as for the serial
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								interface.  For multi-dimensional transforms, any dimensions <code>>
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								1</code> are supported; for one-dimensional transforms, only composite
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								(non-prime) <code>n0</code> are currently supported (unlike the serial
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								FFTW).  Requesting an unsupported transform size will yield a
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								<code>NULL</code> plan.  (As in the serial interface, highly composite sizes
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								generally yield the best performance.)
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								</p>
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								<span id="index-advanced-interface-6"></span>
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								<span id="index-FFTW_005fMPI_005fDEFAULT_005fBLOCK-2"></span>
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								<span id="index-stride-3"></span>
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								<p>The advanced-interface <code>fftw_mpi_plan_many_dft</code> additionally
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								allows you to specify the block sizes for the first dimension
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								(<code>block</code>) of the n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × n<sub>d-1</sub>
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								 input data and the first dimension
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								(<code>tblock</code>) of the n<sub>1</sub> × n<sub>0</sub> × n<sub>2</sub> ×…× n<sub>d-1</sub>
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								 transposed data (at intermediate
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								steps of the transform, and for the output if
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								<code>FFTW_TRANSPOSED_OUT</code> is specified in <code>flags</code>).  These must
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								be the same block sizes as were passed to the corresponding
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								‘<samp>local_size</samp>’ function; you can pass <code>FFTW_MPI_DEFAULT_BLOCK</code>
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								to use FFTW’s default block size as in the basic interface.  Also, the
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								<code>howmany</code> parameter specifies that the transform is of contiguous
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								<code>howmany</code>-tuples rather than individual complex numbers; this
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								corresponds to the same parameter in the serial advanced interface
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								(see <a href="Advanced-Complex-DFTs.html">Advanced Complex DFTs</a>) with <code>stride = howmany</code> and
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								<code>dist = 1</code>.
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								</p>
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								<span id="MPI-flags"></span><h4 class="subsubheading">MPI flags</h4>
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								<p>The <code>flags</code> can be any of those for the serial FFTW
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								(see <a href="Planner-Flags.html">Planner Flags</a>), and in addition may include one or more of
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								the following MPI-specific flags, which improve performance at the
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								cost of changing the output or input data formats.
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								</p>
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								<ul>
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								<li> <span id="index-FFTW_005fMPI_005fSCRAMBLED_005fOUT-2"></span>
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								<span id="index-FFTW_005fMPI_005fSCRAMBLED_005fIN-2"></span>
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								<code>FFTW_MPI_SCRAMBLED_OUT</code>, <code>FFTW_MPI_SCRAMBLED_IN</code>: valid for
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								1d transforms only, these flags indicate that the output/input of the
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								transform are in an undocumented “scrambled” order.  A forward
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								<code>FFTW_MPI_SCRAMBLED_OUT</code> transform can be inverted by a backward
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								<code>FFTW_MPI_SCRAMBLED_IN</code> (times the usual 1/<i>N</i> normalization).
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								See <a href="One_002ddimensional-distributions.html">One-dimensional distributions</a>.
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								</li><li> <span id="index-FFTW_005fMPI_005fTRANSPOSED_005fOUT-2"></span>
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								<span id="index-FFTW_005fMPI_005fTRANSPOSED_005fIN-2"></span>
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								<code>FFTW_MPI_TRANSPOSED_OUT</code>, <code>FFTW_MPI_TRANSPOSED_IN</code>: valid
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								for multidimensional (<code>rnk > 1</code>) transforms only, these flags
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								specify that the output or input of an n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × n<sub>d-1</sub>
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								 transform is
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								transposed to n<sub>1</sub> × n<sub>0</sub> × n<sub>2</sub> ×…× n<sub>d-1</sub>
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								.  See <a href="Transposed-distributions.html">Transposed distributions</a>.
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								</li></ul>
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								<span id="Real_002ddata-MPI-DFTs"></span><h4 class="subsubheading">Real-data MPI DFTs</h4>
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								<span id="index-r2c-4"></span>
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								<p>Plans for real-input/output (r2c/c2r) DFTs (see <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html">Multi-dimensional MPI DFTs of Real Data</a>) are created by:
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								</p>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f2d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f2d-1"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fr2c_005f3d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fr2c"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f2d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f2d-1"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fc2r_005f3d"></span>
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								<span id="index-fftw_005fmpi_005fplan_005fdft_005fc2r"></span>
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								<div class="example">
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								<pre class="example">fftw_plan fftw_mpi_plan_dft_r2c_2d(ptrdiff_t n0, ptrdiff_t n1, 
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								                                   double *in, fftw_complex *out,
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								                                   MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_r2c_2d(ptrdiff_t n0, ptrdiff_t n1, 
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								                                   double *in, fftw_complex *out,
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								                                   MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_r2c_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
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								                                   double *in, fftw_complex *out,
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								                                   MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_r2c(int rnk, const ptrdiff_t *n,
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								                                double *in, fftw_complex *out,
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								                                MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_c2r_2d(ptrdiff_t n0, ptrdiff_t n1, 
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								                                   fftw_complex *in, double *out,
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								                                   MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_c2r_2d(ptrdiff_t n0, ptrdiff_t n1, 
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								                                   fftw_complex *in, double *out,
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								                                   MPI_Comm comm, unsigned flags);
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								fftw_plan fftw_mpi_plan_dft_c2r_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
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								                                   fftw_complex *in, double *out,
							 | 
						||
| 
								 | 
							
								                                   MPI_Comm comm, unsigned flags);
							 | 
						||
| 
								 | 
							
								fftw_plan fftw_mpi_plan_dft_c2r(int rnk, const ptrdiff_t *n,
							 | 
						||
| 
								 | 
							
								                                fftw_complex *in, double *out,
							 | 
						||
| 
								 | 
							
								                                MPI_Comm comm, unsigned flags);
							 | 
						||
| 
								 | 
							
								</pre></div>
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								<p>Similar to the serial interface (see <a href="Real_002ddata-DFTs.html">Real-data DFTs</a>), these
							 | 
						||
| 
								 | 
							
								transform logically n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × n<sub>d-1</sub>
							 | 
						||
| 
								 | 
							
								 real data to/from n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × (n<sub>d-1</sub>/2 + 1)
							 | 
						||
| 
								 | 
							
								 complex
							 | 
						||
| 
								 | 
							
								data, representing the non-redundant half of the conjugate-symmetry
							 | 
						||
| 
								 | 
							
								output of a real-input DFT (see <a href="Multi_002ddimensional-Transforms.html">Multi-dimensional Transforms</a>).
							 | 
						||
| 
								 | 
							
								However, the real array must be stored within a padded n<sub>0</sub> × n<sub>1</sub> × n<sub>2</sub> × … × [2 (n<sub>d-1</sub>/2 + 1)]
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								array (much like the in-place serial r2c transforms, but here for
							 | 
						||
| 
								 | 
							
								out-of-place transforms as well). Currently, only multi-dimensional
							 | 
						||
| 
								 | 
							
								(<code>rnk > 1</code>) r2c/c2r transforms are supported (requesting a plan
							 | 
						||
| 
								 | 
							
								for <code>rnk = 1</code> will yield <code>NULL</code>).  As explained above
							 | 
						||
| 
								 | 
							
								(see <a href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html">Multi-dimensional MPI DFTs of Real Data</a>), the data
							 | 
						||
| 
								 | 
							
								distribution of both the real and complex arrays is given by the
							 | 
						||
| 
								 | 
							
								‘<samp>local_size</samp>’ function called for the dimensions of the
							 | 
						||
| 
								 | 
							
								<em>complex</em> array.  Similar to the other planning functions, the
							 | 
						||
| 
								 | 
							
								input and output arrays are overwritten when the plan is created
							 | 
						||
| 
								 | 
							
								except in <code>FFTW_ESTIMATE</code> mode.
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<p>As for the complex DFTs above, there is an advance interface that
							 | 
						||
| 
								 | 
							
								allows you to manually specify block sizes and to transform contiguous
							 | 
						||
| 
								 | 
							
								<code>howmany</code>-tuples of real/complex numbers:
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<span id="index-fftw_005fmpi_005fplan_005fmany_005fdft_005fr2c"></span>
							 | 
						||
| 
								 | 
							
								<span id="index-fftw_005fmpi_005fplan_005fmany_005fdft_005fc2r"></span>
							 | 
						||
| 
								 | 
							
								<div class="example">
							 | 
						||
| 
								 | 
							
								<pre class="example">fftw_plan fftw_mpi_plan_many_dft_r2c
							 | 
						||
| 
								 | 
							
								              (int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
							 | 
						||
| 
								 | 
							
								               ptrdiff_t iblock, ptrdiff_t oblock,
							 | 
						||
| 
								 | 
							
								               double *in, fftw_complex *out,
							 | 
						||
| 
								 | 
							
								               MPI_Comm comm, unsigned flags);
							 | 
						||
| 
								 | 
							
								fftw_plan fftw_mpi_plan_many_dft_c2r
							 | 
						||
| 
								 | 
							
								              (int rnk, const ptrdiff_t *n, ptrdiff_t howmany,
							 | 
						||
| 
								 | 
							
								               ptrdiff_t iblock, ptrdiff_t oblock,
							 | 
						||
| 
								 | 
							
								               fftw_complex *in, double *out,
							 | 
						||
| 
								 | 
							
								               MPI_Comm comm, unsigned flags);               
							 | 
						||
| 
								 | 
							
								</pre></div>
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								<span id="MPI-r2r-transforms"></span><h4 class="subsubheading">MPI r2r transforms</h4>
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								<span id="index-r2r-4"></span>
							 | 
						||
| 
								 | 
							
								<p>There are corresponding plan-creation routines for r2r
							 | 
						||
| 
								 | 
							
								transforms (see <a href="More-DFTs-of-Real-Data.html">More DFTs of Real Data</a>), currently supporting
							 | 
						||
| 
								 | 
							
								multidimensional (<code>rnk > 1</code>) transforms only (<code>rnk = 1</code> will
							 | 
						||
| 
								 | 
							
								yield a <code>NULL</code> plan):
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<div class="example">
							 | 
						||
| 
								 | 
							
								<pre class="example">fftw_plan fftw_mpi_plan_r2r_2d(ptrdiff_t n0, ptrdiff_t n1,
							 | 
						||
| 
								 | 
							
								                               double *in, double *out,
							 | 
						||
| 
								 | 
							
								                               MPI_Comm comm,
							 | 
						||
| 
								 | 
							
								                               fftw_r2r_kind kind0, fftw_r2r_kind kind1,
							 | 
						||
| 
								 | 
							
								                               unsigned flags);
							 | 
						||
| 
								 | 
							
								fftw_plan fftw_mpi_plan_r2r_3d(ptrdiff_t n0, ptrdiff_t n1, ptrdiff_t n2,
							 | 
						||
| 
								 | 
							
								                               double *in, double *out,
							 | 
						||
| 
								 | 
							
								                               MPI_Comm comm,
							 | 
						||
| 
								 | 
							
								                               fftw_r2r_kind kind0, fftw_r2r_kind kind1, fftw_r2r_kind kind2,
							 | 
						||
| 
								 | 
							
								                               unsigned flags);
							 | 
						||
| 
								 | 
							
								fftw_plan fftw_mpi_plan_r2r(int rnk, const ptrdiff_t *n,
							 | 
						||
| 
								 | 
							
								                            double *in, double *out,
							 | 
						||
| 
								 | 
							
								                            MPI_Comm comm, const fftw_r2r_kind *kind, 
							 | 
						||
| 
								 | 
							
								                            unsigned flags);
							 | 
						||
| 
								 | 
							
								fftw_plan fftw_mpi_plan_many_r2r(int rnk, const ptrdiff_t *n,
							 | 
						||
| 
								 | 
							
								                                 ptrdiff_t iblock, ptrdiff_t oblock,
							 | 
						||
| 
								 | 
							
								                                 double *in, double *out,
							 | 
						||
| 
								 | 
							
								                                 MPI_Comm comm, const fftw_r2r_kind *kind, 
							 | 
						||
| 
								 | 
							
								                                 unsigned flags);
							 | 
						||
| 
								 | 
							
								</pre></div>
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								<p>The parameters are much the same as for the complex DFTs above, except
							 | 
						||
| 
								 | 
							
								that the arrays are of real numbers (and hence the outputs of the
							 | 
						||
| 
								 | 
							
								‘<samp>local_size</samp>’ data-distribution functions should be interpreted as
							 | 
						||
| 
								 | 
							
								counts of real rather than complex numbers).  Also, the <code>kind</code>
							 | 
						||
| 
								 | 
							
								parameters specify the r2r kinds along each dimension as for the
							 | 
						||
| 
								 | 
							
								serial interface (see <a href="Real_002dto_002dReal-Transform-Kinds.html">Real-to-Real Transform Kinds</a>).  See <a href="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html">Other Multi-dimensional Real-data MPI Transforms</a>.
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<span id="MPI-transposition"></span><h4 class="subsubheading">MPI transposition</h4>
							 | 
						||
| 
								 | 
							
								<span id="index-transpose-5"></span>
							 | 
						||
| 
								 | 
							
								
							 | 
						||
| 
								 | 
							
								<p>FFTW also provides routines to plan a transpose of a distributed
							 | 
						||
| 
								 | 
							
								<code>n0</code> by <code>n1</code> array of real numbers, or an array of
							 | 
						||
| 
								 | 
							
								<code>howmany</code>-tuples of real numbers with specified block sizes
							 | 
						||
| 
								 | 
							
								(see <a href="FFTW-MPI-Transposes.html">FFTW MPI Transposes</a>):
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<span id="index-fftw_005fmpi_005fplan_005ftranspose-1"></span>
							 | 
						||
| 
								 | 
							
								<span id="index-fftw_005fmpi_005fplan_005fmany_005ftranspose-1"></span>
							 | 
						||
| 
								 | 
							
								<div class="example">
							 | 
						||
| 
								 | 
							
								<pre class="example">fftw_plan fftw_mpi_plan_transpose(ptrdiff_t n0, ptrdiff_t n1,
							 | 
						||
| 
								 | 
							
								                                  double *in, double *out,
							 | 
						||
| 
								 | 
							
								                                  MPI_Comm comm, unsigned flags);
							 | 
						||
| 
								 | 
							
								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-new_002darray-execution-2"></span>
							 | 
						||
| 
								 | 
							
								<span id="index-fftw_005fmpi_005fexecute_005fr2r-1"></span>
							 | 
						||
| 
								 | 
							
								<p>These plans are used with the <code>fftw_mpi_execute_r2r</code> new-array
							 | 
						||
| 
								 | 
							
								execute function (see <a href="Using-MPI-Plans.html">Using MPI Plans</a>), since they count as (rank
							 | 
						||
| 
								 | 
							
								zero) r2r plans from FFTW’s perspective.
							 | 
						||
| 
								 | 
							
								</p>
							 | 
						||
| 
								 | 
							
								<hr>
							 | 
						||
| 
								 | 
							
								<div class="header">
							 | 
						||
| 
								 | 
							
								<p>
							 | 
						||
| 
								 | 
							
								Next: <a href="MPI-Wisdom-Communication.html" accesskey="n" rel="next">MPI Wisdom Communication</a>, Previous: <a href="MPI-Data-Distribution-Functions.html" accesskey="p" rel="prev">MPI Data Distribution Functions</a>, Up: <a href="FFTW-MPI-Reference.html" accesskey="u" rel="up">FFTW MPI Reference</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
							 | 
						||
| 
								 | 
							
								</div>
							 | 
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								 | 
							
								
							 | 
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								 | 
							
								
							 | 
						||
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								 | 
							
								
							 | 
						||
| 
								 | 
							
								</body>
							 | 
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								 | 
							
								</html>
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