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MPI_Cart_map(3OpenMPI)                                                                MPI_Cart_map(3OpenMPI)



NAME
       MPI_Cart_map  -  Maps process to Cartesian topology information.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Cart_map(MPI_Comm comm, int ndims, int *dims,
            int *periods, int *newrank)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_CART_MAP(COMM, NDIMS, DIMS, PERIODS, NEWRANK, IERROR)
            INTEGER   COMM, NDIMS, DIMS(*), NEWRANK, IERROR
            LOGICAL   PERIODS(*)


C++ Syntax
       #include <mpi.h>
       int Cartcomm::Map(int ndims, const int dims[],
            const bool periods[]) const


INPUT PARAMETERS
       comm      Input communicator (handle).

       ndims     Number of dimensions of Cartesian structure (integer).

       dims      Integer  array  of  size ndims specifying the number of processes in each coordinate direc-tion. direction.
                 tion.

       periods   Logical array of size ndims specifying the periodicity  specification  in  each  coordinate
                 direction.


OUTPUT PARAMETERS
       newrank   Reordered  rank of the calling process; MPI_UNDEFINED if calling process does not belong to
                 grid (integer).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Cart_map and MPI_Graph_map can be used to implement all other topology functions. In general they
       will  not  be  called  by the user directly, unless he or she is creating additional virtual topology
       capability other than that provided by MPI.

       MPI_Cart_map computes an "optimal" placement for the calling process on the physical machine. A  pos-sible possible
       sible  implementation  of this function is to always return the rank of the calling process, that is,
       not to perform any reordering.


ERRORS
       Almost all MPI routines return an error value; C routines as the value of the  function  and  Fortran
       routines  in  the  last argument. C++ functions do not return errors. If the default error handler is
       set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to  throw
       an MPI:Exception object.

       Before  the  error value is returned, the current MPI error handler is called. By default, this error
       handler aborts the MPI job, except for I/O function errors. The error handler  may  be  changed  with
       MPI_Comm_set_errhandler;  the  predefined  error handler MPI_ERRORS_RETURN may be used to cause error
       values to be returned. Note that MPI does not guarantee that an MPI  program  can  continue  past  an
       error.


SEE ALSO
       MPI_Graph_map



Open MPI 1.2                                   September 2006                         MPI_Cart_map(3OpenMPI)