NAME

       MPI_Cart_create - Makes a new communicator to which Cartesian topology information has been attached.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Cart_create(MPI_Comm comm_old, int ndims, int *dims,
            int *periods, int reorder, MPI_Comm *comm_cart)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_CART_CREATE(COMM_OLD, NDIMS, DIMS, PERIODS, REORDER,
                 COMM_CART, IERROR)
            INTEGER   COMM_OLD, NDIMS, DIMS(*), COMM_CART, IERROR
            LOGICAL   PERIODS(*), REORDER

C++ Syntax

       #include <mpi.h>
       Cartcomm Intracomm::Create_cart(int ndims, const int dims[],
            const bool periods[], bool reorder) const

INPUT PARAMETERS

       comm_old  Input communicator (handle).

       ndims     Number of dimensions of Cartesian grid (integer).

       dims      Integer array of size ndims specifying the number of processes in each dimension.

       periods   Logical  array  of  size ndims specifying whether the grid is periodic (true) or not (false) in
                 each dimension.

       reorder   Ranking may be reordered (true) or not (false) (logical).

OUTPUT PARAMETERS

       comm_cart Communicator with new Cartesian topology (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Cart_create returns a handle to a new communicator to which the  Cartesian  topology  information  is
       attached.  If  reorder = false then the rank of each process in the new group is identical to its rank in
       the old group. Otherwise, the function may reorder the  processes  (possibly  so  as  to  choose  a  good
       embedding  of the virtual topology onto the physical machine). If the total size of the Cartesian grid is
       smaller than the size of the group of comm, then some processes are returned MPI_COMM_NULL, in analogy to
       MPI_Comm_split. The call is erroneous if it specifies a grid that is larger than the group size.

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.