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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 37bf6b4a2645
children
rev   line source
Chris@10 1 <html lang="en">
Chris@10 2 <head>
Chris@10 3 <title>Using MPI Plans - FFTW 3.3.3</title>
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Chris@10 48 <div class="node">
Chris@10 49 <a name="Using-MPI-Plans"></a>
Chris@10 50 <p>
Chris@10 51 Next:&nbsp;<a rel="next" accesskey="n" href="MPI-Data-Distribution-Functions.html#MPI-Data-Distribution-Functions">MPI Data Distribution Functions</a>,
Chris@10 52 Previous:&nbsp;<a rel="previous" accesskey="p" href="MPI-Initialization.html#MPI-Initialization">MPI Initialization</a>,
Chris@10 53 Up:&nbsp;<a rel="up" accesskey="u" href="FFTW-MPI-Reference.html#FFTW-MPI-Reference">FFTW MPI Reference</a>
Chris@10 54 <hr>
Chris@10 55 </div>
Chris@10 56
Chris@10 57 <h4 class="subsection">6.12.3 Using MPI Plans</h4>
Chris@10 58
Chris@10 59 <p>Once an MPI plan is created, you can execute and destroy it using
Chris@10 60 <code>fftw_execute</code>, <code>fftw_destroy_plan</code>, and the other functions
Chris@10 61 in the serial interface that operate on generic plans (see <a href="Using-Plans.html#Using-Plans">Using Plans</a>).
Chris@10 62
Chris@10 63 <p><a name="index-collective-function-438"></a><a name="index-MPI-communicator-439"></a>The <code>fftw_execute</code> and <code>fftw_destroy_plan</code> functions, applied to
Chris@10 64 MPI plans, are <em>collective</em> calls: they must be called for all processes
Chris@10 65 in the communicator that was used to create the plan.
Chris@10 66
Chris@10 67 <p><a name="index-new_002darray-execution-440"></a>You must <em>not</em> use the serial new-array plan-execution functions
Chris@10 68 <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
Chris@10 69 problem type, and there are specific new-array execute functions for MPI plans:
Chris@10 70
Chris@10 71 <p><a name="index-fftw_005fmpi_005fexecute_005fdft-441"></a><a name="index-fftw_005fmpi_005fexecute_005fdft_005fr2c-442"></a><a name="index-fftw_005fmpi_005fexecute_005fdft_005fc2r-443"></a><a name="index-fftw_005fmpi_005fexecute_005fr2r-444"></a>
Chris@10 72 <pre class="example"> void fftw_mpi_execute_dft(fftw_plan p, fftw_complex *in, fftw_complex *out);
Chris@10 73 void fftw_mpi_execute_dft_r2c(fftw_plan p, double *in, fftw_complex *out);
Chris@10 74 void fftw_mpi_execute_dft_c2r(fftw_plan p, fftw_complex *in, double *out);
Chris@10 75 void fftw_mpi_execute_r2r(fftw_plan p, double *in, double *out);
Chris@10 76 </pre>
Chris@10 77 <p><a name="index-alignment-445"></a><a name="index-fftw_005fmalloc-446"></a>These functions have the same restrictions as those of the serial
Chris@10 78 new-array execute functions. They are <em>always</em> safe to apply to
Chris@10 79 the <em>same</em> <code>in</code> and <code>out</code> arrays that were used to
Chris@10 80 create the plan. They can only be applied to new arrarys if those
Chris@10 81 arrays have the same types, dimensions, in-placeness, and alignment as
Chris@10 82 the original arrays, where the best way to ensure the same alignment
Chris@10 83 is to use FFTW's <code>fftw_malloc</code> and related allocation functions
Chris@10 84 for all arrays (see <a href="Memory-Allocation.html#Memory-Allocation">Memory Allocation</a>). Note that distributed
Chris@10 85 transposes (see <a href="FFTW-MPI-Transposes.html#FFTW-MPI-Transposes">FFTW MPI Transposes</a>) use
Chris@10 86 <code>fftw_mpi_execute_r2r</code>, since they count as rank-zero r2r plans
Chris@10 87 from FFTW's perspective.
Chris@10 88
Chris@10 89 </body></html>
Chris@10 90