SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Type_ub(MPI_Datatype datatype, MPI_Aint *displacement)

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

          MPI_TYPE_UB(DATATYPE, DISPLACEMENT, IERROR)
               INTEGER DATATYPE, DISPLACEMENT, IERROR

INPUT PARAMETER

       • datatype: Datatype (handle).

OUTPUT PARAMETERS

       • displacement: Displacement of upper bound from origin, in bytes (integer).

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

DESCRIPTION

       Note that use of this routine is deprecated as of MPI-2. Please use MPI_Type_get_extent instead.

       MPI_Type_ub returns the upper bound of a  data  type.  This  will  differ  from  zero  if  the  type  was
       constructed using MPI_UB. The upper bound will take into account any alignment considerations.

       The  “pseudo-datatypes,”  MPI_LB  and  MPI_UB, can be used, respectively, to mark the upper bound (or the
       lower bound) of a datatype. These pseudo-datatypes occupy no space (extent (MPI_LB) = extent (MPI_UB) =0.
       They do not affect the size or count of a datatype, and do not affect the context of  a  message  created
       with  this  datatype.  However, they do affect the definition of the extent of a datatype and, therefore,
       affect the outcome of a replication of this datatype by a datatype constructor.

       In general, if

          Typemap = {(type(0), disp(0)), ..., (type(n-1), disp(n-1))}

       then the lower bound of Typemap is defined to be

                        (min(j) disp(j)                          if no entry has
          lb(Typemap) = (                                        basic type lb
                        (min(j) {disp(j) such that type(j) = lb} otherwise

       Similarly, the upper bound of Typemap is defined to be

                        (max(j) disp(j) + sizeof(type(j) = lb}   if no entry has
          ub(Typemap) = (                                        basic type ub
                        (max(j) {disp(j) such that type(j) = ub} otherwise

       Then

          extent(Typemap) = ub(Typemap) - lb(Typemap)

       If type(i) requires alignment to a byte address that  is  a  multiple  of  k(i),  then  e  is  the  least
       nonnegative increment needed to round extent(Typemap) to the next multiple of max(i) k(i).

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_Type_get_extent

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                    MPI_TYPE_UB(3)