plucky (3) MPI_Cart_map.openmpi.3.gz

SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Cart_map(MPI_Comm comm, int ndims, const int dims[],
              const int periods[], int *newrank)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'

          MPI_CART_MAP(COMM, NDIMS, DIMS, PERIODS, NEWRANK, IERROR)
              INTEGER COMM, NDIMS, DIMS(*), NEWRANK, IERROR
              LOGICAL PERIODS(*)

   Fortran 2008 Syntax
          USE mpi_f08

          MPI_Cart_map(comm, ndims, dims, periods, newrank, ierror)
              TYPE(MPI_Comm), INTENT(IN) :: comm
              INTEGER, INTENT(IN) :: ndims, dims(ndims)
              LOGICAL, INTENT(IN) :: periods(ndims)
              INTEGER, INTENT(OUT) :: newrank
              INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       • comm : Input communicator (handle).

       • ndims : Number of dimensions of Cartesian structure (integer).

       •

         dims (Integer array of size ndims specifying the number of processes)
                in each coordinate direction.

       •

         periods (Logical array of size ndims specifying the periodicity)
                specification in each coordinate direction.

OUTPUT PARAMETERS

       •

         newrank (Reordered rank of the calling process; MPI_UNDEFINED if)
                calling process does not belong to grid (integer).

       • ierror : Fortran only: Error status (integer).

DESCRIPTION

       MPI_Cart_map  and  MPI_Graph_map  can  be used to implement all other topology functions. In general they
       will not be called by the user directly, unless  he  or  she  is  creating  additional  virtual  topology
       capability  other than that provided by MPI. MPI_Cart_map computes an “optimal” placement for the calling
       process on the physical machine. A possible implementation of this function is to always return the  rank
       of the calling process, that is, not to perform any reordering.

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.

       SEE ALSO:

          • MPI_Graph_map

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                   MPI_CART_MAP(3)