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