oracular (3) MPI_Cart_map.openmpi.3.gz

Provided by: openmpi-doc_4.1.6-13.3ubuntu2_all bug

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, const int dims[],
            const int periods[], int *newrank)


Fortran Syntax
       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_CART_MAP(COMM, NDIMS, DIMS, PERIODS, NEWRANK, IERROR)
            INTEGER   COMM, NDIMS, DIMS(*), NEWRANK, IERROR
            LOGICAL   PERIODS(*)


Fortran 2008 Syntax
       USE mpi_f08
       MPI_Cart_map(comm, ndims, dims, periods, newrank, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(IN) :: ndims, dims(ndims)
            LOGICAL, INTENT(IN) :: periods(ndims)
            INTEGER, INTENT(OUT) :: newrank
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror


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