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| cannam@127 | 25 <title>FFTW 3.3.5: Using MPI Plans</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="Using-MPI-Plans"></a> | 
| cannam@127 | 73 <div class="header"> | 
| cannam@127 | 74 <p> | 
| cannam@127 | 75 Next: <a href="MPI-Data-Distribution-Functions.html#MPI-Data-Distribution-Functions" accesskey="n" rel="next">MPI Data Distribution Functions</a>, Previous: <a href="MPI-Initialization.html#MPI-Initialization" accesskey="p" rel="prev">MPI Initialization</a>, Up: <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" 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#Concept-Index" title="Index" rel="index">Index</a>]</p> | 
| cannam@127 | 76 </div> | 
| cannam@127 | 77 <hr> | 
| cannam@127 | 78 <a name="Using-MPI-Plans-1"></a> | 
| cannam@127 | 79 <h4 class="subsection">6.12.3 Using MPI Plans</h4> | 
| cannam@127 | 80 | 
| cannam@127 | 81 <p>Once an MPI plan is created, you can execute and destroy it using | 
| cannam@127 | 82 <code>fftw_execute</code>, <code>fftw_destroy_plan</code>, and the other functions | 
| cannam@127 | 83 in the serial interface that operate on generic plans (see <a href="Using-Plans.html#Using-Plans">Using Plans</a>). | 
| cannam@127 | 84 </p> | 
| cannam@127 | 85 <a name="index-collective-function-3"></a> | 
| cannam@127 | 86 <a name="index-MPI-communicator-1"></a> | 
| cannam@127 | 87 <p>The <code>fftw_execute</code> and <code>fftw_destroy_plan</code> functions, applied to | 
| cannam@127 | 88 MPI plans, are <em>collective</em> calls: they must be called for all processes | 
| cannam@127 | 89 in the communicator that was used to create the plan. | 
| cannam@127 | 90 </p> | 
| cannam@127 | 91 <a name="index-new_002darray-execution-1"></a> | 
| cannam@127 | 92 <p>You must <em>not</em> use the serial new-array plan-execution functions | 
| cannam@127 | 93 <code>fftw_execute_dft</code> and so on (see <a href="New_002darray-Execute-Functions.html#New_002darray-Execute-Functions">New-array Execute Functions</a>) with MPI plans.  Such functions are specialized to the | 
| cannam@127 | 94 problem type, and there are specific new-array execute functions for MPI plans: | 
| cannam@127 | 95 </p> | 
| cannam@127 | 96 <a name="index-fftw_005fmpi_005fexecute_005fdft"></a> | 
| cannam@127 | 97 <a name="index-fftw_005fmpi_005fexecute_005fdft_005fr2c"></a> | 
| cannam@127 | 98 <a name="index-fftw_005fmpi_005fexecute_005fdft_005fc2r"></a> | 
| cannam@127 | 99 <a name="index-fftw_005fmpi_005fexecute_005fr2r"></a> | 
| cannam@127 | 100 <div class="example"> | 
| cannam@127 | 101 <pre class="example">void fftw_mpi_execute_dft(fftw_plan p, fftw_complex *in, fftw_complex *out); | 
| cannam@127 | 102 void fftw_mpi_execute_dft_r2c(fftw_plan p, double *in, fftw_complex *out); | 
| cannam@127 | 103 void fftw_mpi_execute_dft_c2r(fftw_plan p, fftw_complex *in, double *out); | 
| cannam@127 | 104 void fftw_mpi_execute_r2r(fftw_plan p, double *in, double *out); | 
| cannam@127 | 105 </pre></div> | 
| cannam@127 | 106 | 
| cannam@127 | 107 <a name="index-alignment-3"></a> | 
| cannam@127 | 108 <a name="index-fftw_005fmalloc-6"></a> | 
| cannam@127 | 109 <p>These functions have the same restrictions as those of the serial | 
| cannam@127 | 110 new-array execute functions.  They are <em>always</em> safe to apply to | 
| cannam@127 | 111 the <em>same</em> <code>in</code> and <code>out</code> arrays that were used to | 
| cannam@127 | 112 create the plan.  They can only be applied to new arrarys if those | 
| cannam@127 | 113 arrays have the same types, dimensions, in-placeness, and alignment as | 
| cannam@127 | 114 the original arrays, where the best way to ensure the same alignment | 
| cannam@127 | 115 is to use FFTW’s <code>fftw_malloc</code> and related allocation functions | 
| cannam@127 | 116 for all arrays (see <a href="Memory-Allocation.html#Memory-Allocation">Memory Allocation</a>).  Note that distributed | 
| cannam@127 | 117 transposes (see <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes">FFTW MPI Transposes</a>) use | 
| cannam@127 | 118 <code>fftw_mpi_execute_r2r</code>, since they count as rank-zero r2r plans | 
| cannam@127 | 119 from FFTW’s perspective. | 
| cannam@127 | 120 </p> | 
| cannam@127 | 121 <hr> | 
| cannam@127 | 122 <div class="header"> | 
| cannam@127 | 123 <p> | 
| cannam@127 | 124 Next: <a href="MPI-Data-Distribution-Functions.html#MPI-Data-Distribution-Functions" accesskey="n" rel="next">MPI Data Distribution Functions</a>, Previous: <a href="MPI-Initialization.html#MPI-Initialization" accesskey="p" rel="prev">MPI Initialization</a>, Up: <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" 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#Concept-Index" title="Index" rel="index">Index</a>]</p> | 
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