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
- 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.