MPI_Cart_map(3)                    Open MPI                    MPI_Cart_map(3)



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 direction.

       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 possible 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



1.4.1                            Jan 14, 2010                  MPI_Cart_map(3)
