MPI_Cart_create(3) Open MPI MPI_Cart_create(3)
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, const int dims[],
const int periods[], int reorder, MPI_Comm *comm_cart)
Fortran Syntax
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
Fortran 2008 Syntax
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
C++ Syntax
#include <mpi.h>
Cartcomm Intracomm.Create_cart(int ndims, 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 pro-
cesses 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 phys-
ical 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++ func-
tions 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.
4.1.2 Nov 24, 2021 MPI_Cart_create(3)
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