NAME

       MPI_Is_thread_main - Determines if thread called MPI_Init

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Is_thread_main(int *flag)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_IS_THREAD_MAIN(FLAG, IERROR)
            LOGICAL   FLAG
            INTEGER   IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Is_thread_main(flag, ierror)
            LOGICAL, INTENT(OUT) :: flag
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       bool MPI::Is_thread_main()

OUTPUT PARAMETERS

       flag      True if calling thread is main thread (boolean).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Is_thread_main is called by a thread to find out whether the caller is the main thread
       (that is, the thread that called MPI_Init or MPI_Init_thread).

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran  routines in the last argument. C++ functions do not return errors. If the default
       error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then  on  error  the  C++  exception
       mechanism will be used to throw an MPI::Exception object.

       Before  the  error value is returned, the current MPI error handler is called. By default,
       this error handler aborts the MPI job, except for I/O function errors. The  error  handler
       may    be   changed   with   MPI_Comm_set_errhandler;   the   predefined   error   handler
       MPI_ERRORS_RETURN may be used to cause error values to be returned. 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 ALSO

       MPI_Init
       MPI_Init_thread