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Once an MPI plan is created, you can execute and destroy it using
cannam@95: fftw_execute, fftw_destroy_plan, and the other functions
cannam@95: in the serial interface that operate on generic plans (see Using Plans).
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The fftw_execute and fftw_destroy_plan functions, applied to
cannam@95: MPI plans, are collective calls: they must be called for all processes
cannam@95: in the communicator that was used to create the plan.
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You must not use the serial new-array plan-execution functions
cannam@95: fftw_execute_dft and so on (see New-array Execute Functions) with MPI plans. Such functions are specialized to the
cannam@95: problem type, and there are specific new-array execute functions for MPI plans:
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void fftw_mpi_execute_dft(fftw_plan p, fftw_complex *in, fftw_complex *out); cannam@95: void fftw_mpi_execute_dft_r2c(fftw_plan p, double *in, fftw_complex *out); cannam@95: void fftw_mpi_execute_dft_c2r(fftw_plan p, fftw_complex *in, double *out); cannam@95: void fftw_mpi_execute_r2r(fftw_plan p, double *in, double *out); cannam@95:cannam@95:
These functions have the same restrictions as those of the serial
cannam@95: new-array execute functions. They are always safe to apply to
cannam@95: the same in and out arrays that were used to
cannam@95: create the plan. They can only be applied to new arrarys if those
cannam@95: arrays have the same types, dimensions, in-placeness, and alignment as
cannam@95: the original arrays, where the best way to ensure the same alignment
cannam@95: is to use FFTW's fftw_malloc and related allocation functions
cannam@95: for all arrays (see Memory Allocation). Note that distributed
cannam@95: transposes (see FFTW MPI Transposes) use
cannam@95: fftw_mpi_execute_r2r, since they count as rank-zero r2r plans
cannam@95: from FFTW's perspective.
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