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diff src/fftw-3.3.3/doc/html/Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html @ 95:89f5e221ed7b
Add FFTW3
| author | Chris Cannam <cannam@all-day-breakfast.com> |
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| date | Wed, 20 Mar 2013 15:35:50 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.3/doc/html/Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms.html Wed Mar 20 15:35:50 2013 +0000 @@ -0,0 +1,104 @@ +<html lang="en"> +<head> +<title>Other Multi-dimensional Real-data MPI Transforms - FFTW 3.3.3</title> +<meta http-equiv="Content-Type" content="text/html"> +<meta name="description" content="FFTW 3.3.3"> +<meta name="generator" content="makeinfo 4.13"> +<link title="Top" rel="start" href="index.html#Top"> +<link rel="up" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI" title="Distributed-memory FFTW with MPI"> +<link rel="prev" href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data" title="Multi-dimensional MPI DFTs of Real Data"> +<link rel="next" href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes" title="FFTW MPI Transposes"> +<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> +<!-- +This manual is for FFTW +(version 3.3.3, 25 November 2012). + +Copyright (C) 2003 Matteo Frigo. + +Copyright (C) 2003 Massachusetts Institute of Technology. + + Permission is granted to make and distribute verbatim copies of + this manual provided the copyright notice and this permission + notice are preserved on all copies. + + Permission is granted to copy and distribute modified versions of + this manual under the conditions for verbatim copying, provided + that the entire resulting derived work is distributed under the + terms of a permission notice identical to this one. + + Permission is granted to copy and distribute translations of this + manual into another language, under the above conditions for + modified versions, except that this permission notice may be + stated in a translation approved by the Free Software Foundation. + --> +<meta http-equiv="Content-Style-Type" content="text/css"> +<style type="text/css"><!-- + pre.display { font-family:inherit } + pre.format { font-family:inherit } + pre.smalldisplay { font-family:inherit; font-size:smaller } + pre.smallformat { font-family:inherit; font-size:smaller } + pre.smallexample { font-size:smaller } + pre.smalllisp { font-size:smaller } + span.sc { font-variant:small-caps } + span.roman { font-family:serif; font-weight:normal; } + span.sansserif { font-family:sans-serif; font-weight:normal; } +--></style> +</head> +<body> +<div class="node"> +<a name="Other-Multi-dimensional-Real-data-MPI-Transforms"></a> +<a name="Other-Multi_002ddimensional-Real_002ddata-MPI-Transforms"></a> +<p> +Next: <a rel="next" accesskey="n" href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes">FFTW MPI Transposes</a>, +Previous: <a rel="previous" accesskey="p" href="Multi_002ddimensional-MPI-DFTs-of-Real-Data.html#Multi_002ddimensional-MPI-DFTs-of-Real-Data">Multi-dimensional MPI DFTs of Real Data</a>, +Up: <a rel="up" accesskey="u" href="Distributed_002dmemory-FFTW-with-MPI.html#Distributed_002dmemory-FFTW-with-MPI">Distributed-memory FFTW with MPI</a> +<hr> +</div> + +<h3 class="section">6.6 Other multi-dimensional Real-Data MPI Transforms</h3> + +<p><a name="index-r2r-393"></a>FFTW's MPI interface also supports multi-dimensional ‘<samp><span class="samp">r2r</span></samp>’ +transforms of all kinds supported by the serial interface +(e.g. discrete cosine and sine transforms, discrete Hartley +transforms, etc.). Only multi-dimensional ‘<samp><span class="samp">r2r</span></samp>’ transforms, not +one-dimensional transforms, are currently parallelized. + + <p><a name="index-fftw_005fr2r_005fkind-394"></a>These are used much like the multidimensional complex DFTs discussed +above, except that the data is real rather than complex, and one needs +to pass an r2r transform kind (<code>fftw_r2r_kind</code>) for each +dimension as in the serial FFTW (see <a href="More-DFTs-of-Real-Data.html#More-DFTs-of-Real-Data">More DFTs of Real Data</a>). + + <p>For example, one might perform a two-dimensional L × M that is +an REDFT10 (DCT-II) in the first dimension and an RODFT10 (DST-II) in +the second dimension with code like: + +<pre class="example"> const ptrdiff_t L = ..., M = ...; + fftw_plan plan; + double *data; + ptrdiff_t alloc_local, local_n0, local_0_start, i, j; + + /* <span class="roman">get local data size and allocate</span> */ + alloc_local = fftw_mpi_local_size_2d(L, M, MPI_COMM_WORLD, + &local_n0, &local_0_start); + data = fftw_alloc_real(alloc_local); + + /* <span class="roman">create plan for in-place REDFT10 x RODFT10</span> */ + plan = fftw_mpi_plan_r2r_2d(L, M, data, data, MPI_COMM_WORLD, + FFTW_REDFT10, FFTW_RODFT10, FFTW_MEASURE); + + /* <span class="roman">initialize data to some function</span> my_function(x,y) */ + for (i = 0; i < local_n0; ++i) for (j = 0; j < M; ++j) + data[i*M + j] = my_function(local_0_start + i, j); + + /* <span class="roman">compute transforms, in-place, as many times as desired</span> */ + fftw_execute(plan); + + fftw_destroy_plan(plan); +</pre> + <p><a name="index-fftw_005falloc_005freal-395"></a>Notice that we use the same ‘<samp><span class="samp">local_size</span></samp>’ functions as we did for +complex data, only now we interpret the sizes in terms of real rather +than complex values, and correspondingly use <code>fftw_alloc_real</code>. + +<!-- --> + </body></html> +