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MPI_Cart_create - Makes a new communicator to which Cartesian
topology information has been attached.
#include <mpi.h>
int MPI_Cart_create(MPI_Comm comm_old, int ndims, const int dims[],
const int periods[], int reorder, MPI_Comm *comm_cart)
USE MPI
! or the older form: 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
USE mpi_f08
MPI_Cart_create(comm_old, ndims, dims, periods, reorder, comm_cart, ierror)
TYPE(MPI_Comm), INTENT(IN) :: comm_old
INTEGER, INTENT(IN) :: ndims, dims(ndims)
LOGICAL, INTENT(IN) :: periods(ndims), reorder
TYPE(MPI_Comm), INTENT(OUT) :: comm_cart
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- 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).
- comm_cart
- Communicator with new Cartesian topology (handle).
- IERROR
- Fortran only: Error status (integer).
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.
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.
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