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

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 return result of the function and
       Fortran routines in the last argument.

       Before the error value is returned, the current MPI  error  handler  associated  with  the  communication
       object  (e.g.,  communicator, window, file) is called.  If no communication object is associated with the
       MPI call, then the call is considered attached to MPI_COMM_SELF and will call the  associated  MPI  error
       handler.   When   MPI_COMM_SELF   is   not  initialized  (i.e.,  before  MPI_Init/MPI_Init_thread,  after
       MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial  error  handler.
       The  initial  error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using
       the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info  key  to  MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.   If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
       error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is  called  for  all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called  on  a  communicator,  it  acts  as if MPI_Abort was called on that communicator. If called on a
         window or file, acts as if MPI_Abort was called on a communicator containing the group of processes  in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       See the Error Handling section of the MPI-3.1 standard for more information.

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Jun 07, 2025                                MPI_CART_CREATE(3)