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       MPI_Type_get_name -  Get the print name for a datatype


       int MPI_Type_get_name(MPI_Datatype datatype, char *type_name, int *resultlen)


              - datatype whose name is to be returned (handle)


              -  the  name  previously  stored on the datatype, or a empty string if no such name
              exists (string)
              - length of returned name (integer)


       This routine is thread and interrupt safe only if no MPI routine that updates or frees the
       same MPI object may be called concurrently with this routine.

       The  MPI standard defined a thread-safe interface but this does not mean that all routines
       may be called without any thread locks.  For example, two  threads  must  not  attempt  to
       change  the contents of the same MPI_Info object concurrently.  The user is responsible in
       this case for using some mechanism, such as thread locks, to ensure that only  one  thread
       at a time makes use of this routine.


       The  MPI 1.1 specification, in the section on opaque objects, explicitly disallows freeing
       a null communicator.  The text from the standard is:
       A null handle argument is an erroneous IN argument in MPI calls, unless an
       exception is explicitly stated in the text that defines the function. Such
       exception is allowed for handles to request objects in Wait and Test calls
       (sections Communication Completion and Multiple Completions ). Otherwise, a
       null handle can only be passed to a function that allocates a new object and
       returns a reference to it in the handle.


       All MPI routines in Fortran (except for MPI_WTIME  and  MPI_WTICK  )  have  an  additional
       argument  ierr  at  the  end  of  the  argument list.  ierr is an integer and has the same
       meaning as the  return  value  of  the  routine  in  C.   In  Fortran,  MPI  routines  are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.


       All  MPI  routines  (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as
       the value of the function and Fortran routines in the last argument.  Before the value  is
       returned,  the current MPI error handler is called.  By default, this error handler aborts
       the MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler  (for
       communicators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_errhandler (for RMA
       windows).  The MPI-1 routine MPI_Errhandler_set may be used but  its  use  is  deprecated.
       The  predefined  error  handler  MPI_ERRORS_RETURN may be used to cause error values to be
       returned.  Note that MPI does not guarentee that an  MPI  program  can  continue  past  an
       error; however, MPI implementations will attempt to continue whenever possible.

              - No error; MPI routine completed successfully.
              -  Invalid datatype argument.  Additionally, this error can occur if an uncommitted
              MPI_Datatype (see MPI_Type_commit ) is used in a communication call.
              - Invalid argument.  Some argument is invalid and is not identified by  a  specific
              error class (e.g., MPI_ERR_RANK ).

                                            11/21/2018                       MPI_Type_get_name(3)