Exercise1 MPI Bcast is used to send data form one process to another int MPI_Bca

Question

Exercise1 MPI Bcast is used to send data form one process to another int MPI_Bcast( void* i In MPI_Datatype i nt MPIComm data_p count datatype source proc comm /* in/ out */ / in /s in In /s in 0 Write a program that 1. Asks form the user to enter an integer number 2. Reads this value and distributes the value to all of the MPI processes 3. Each process after having received the number, should print the received values along with its rank. 4. The program should be continuous should be read until a negative integer is given as input

Explanation / Answer

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.

MPI_SUCCESS

No error; MPI routine completed successfully.

MPI_ERR_COMM

Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).

MPI_ERR_COUNT

Invalid count argument. Count arguments must be non-negative; a count of zero is often valid.

MPI_ERR_TYPE

Invalid datatype argument. May be an uncommitted MPI_Datatype (see MPI_Type_commit).

MPI_ERR_BUFFER

Invalid buffer pointer. Usually a null buffer where one is not valid.

MPI_ERR_ROOT

Invalid root. The root must be specified as a rank in the communicator. Ranks must be between zero and the size of the communicator minus one.

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