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MPIL_Type_id(3)                     LAM/MPI                    MPIL_Type_id(3)

NAME
       MPIL_Type_id -  LAM/MPI-specific function to return the type ID of an
       MPI datatype

SYNOPSIS
       #include <mpi.h>
       int MPIL_Type_id(MPI_Datatype dtype, int *ptid)

INPUT PARAMETER
       dtype  - MPI datatype (handle)

OUTPUT PARAMETER
       ptid   - datatype ID (integer)

NOTES
       In the LAM implementation of MPI, each communicator has an integer
       context ID associated with it for synchronizing on different contexts.
       This ID is global to all the processes in the communicator's group, and
       uniquely identifies that communicator for each process.  These
       properties allow the processes to safely exchange messages without
       interference from operations on other communicators.

       The MPI standard does not provide a way to access/view this
       implementation-dependent synchronization since communicators are opaque
       objects.  Users do not need such access for normal MPI operations.  On
       the other hand, when debugging MPI applications, the opaque nature of
       communicators hinders the user's efforts.  This is especially true on
       fully observable systems such as LAM, where users can monitor the full
       state of the processes and message queues, which includes the context
       ID (see mpitask (1) and mpimsg (1)).

       This is a LAM/MPI-specific function and is intended mainly for
       debugging.  If this function is used, it should be used in conjunction
       with the LAM_MPI C preprocessor macro

       #if LAM_MPI
       int tid
       MPIL_Type_id(MPI_INT, &tid);
       #endif

NOTES FOR FORTRAN
       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.

ERRORS
       If an error occurs in an MPI function, the current MPI error handler is
       called to handle it.  By default, this error handler aborts the MPI
       job.  The error handler may be changed with MPI_Errhandler_set ; the
       predefined error handler MPI_ERRORS_RETURN may be used to cause error
       values to be returned (in C and Fortran; this error handler is less
       useful in with the C++ MPI bindings.  The predefined error handler
       MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
       needs to be recovered).  Note that MPI does not guarantee that an MPI
       program can continue past an error.

       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.  The C++ bindings for MPI do not return error
       values; instead, error values are communicated by throwing exceptions
       of type MPI::Exception (but not by default).  Exceptions are only
       thrown if the error value is not MPI::SUCCESS .

       Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
       functions will return upon an error, there will be no way to recover
       what the actual error value was.
       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_TYPE
              - Invalid datatype argument.  May be an uncommitted MPI_Datatype
              (see MPI_Type_commit ).
       MPI_ERR_ARG
              - Invalid argument.  Some argument is invalid and is not
              identified by a specific error class.  This is typically a NULL
              pointer or other such error.

SEE ALSO
       MPIL_Comm_gps, MPIL_Comm_id

LOCATION
       mpil_id.c

LAM/MPI 7.1.5b2                    6/24/2006                   MPIL_Type_id(3)