MPI_Comm_free(3) MPI MPI_Comm_free(3) NAME MPI_Comm_free - Marks the communicator object for deallocation SYNOPSIS #include "mpi.h" int MPI_Comm_free ( MPI_Comm *commp ) INPUT PARAMETER comm - communicator to be destroyed (handle) NULL HANDLES 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. 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 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_Errhandler_set ; the prede- fined 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. MPI_SUCCESS - No error; MPI routine completed successfully. MPI_ERR_COMM - Invalid communicator. A common error is to use a null commu- nicator in a call (not even allowed in MPI_Comm_rank ). MPI_ERR_ARG - Invalid argument. Some argument is invalid and is not identi- fied by a specific error class (e.g., MPI_ERR_RANK ). LOCATION comm_free.c 10/31/2002 MPI_Comm_free(3)