1: ! Synchronized printing: Fortran Example
  2: #include <petsc/finclude/petscsys.h>
  3: program main
  4:   use petscmpi  ! or mpi or mpi_f08
  5:   use petscsys

  7:   implicit none
  8:   PetscErrorCode                    :: ierr
  9:   PetscMPIInt                       :: rank, size
 10:   character(len=PETSC_MAX_PATH_LEN) :: outputString

 12:   ! Every PETSc program should begin with the PetscInitialize() routine.

 14:   PetscCallA(PetscInitialize(ierr))

 16:   ! The following MPI calls return the number of processes
 17:   ! being used and the rank of this process in the group

 19:   PetscCallMPIA(MPI_Comm_size(MPI_COMM_WORLD, size, ierr))
 20:   PetscCallMPIA(MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr))

 22:   ! Here we would like to print only one message that represents
 23:   ! all the processes in the group
 24:   write (outputString, *) 'No of Processors = ', size, ', rank = ', rank, '\n'
 25:   PetscCallA(PetscPrintf(PETSC_COMM_WORLD, outputString, ierr))

 27:   write (outputString, *) rank, 'Synchronized Hello World\n'
 28:   PetscCallA(PetscSynchronizedPrintf(PETSC_COMM_WORLD, outputString, ierr))

 30:   write (outputString, *) rank, 'Synchronized Hello World - Part II\n'
 31:   PetscCallA(PetscSynchronizedPrintf(PETSC_COMM_WORLD, outputString, ierr))
 32:   PetscCallA(PetscSynchronizedFlush(PETSC_COMM_WORLD, PETSC_STDOUT, ierr))

 34:   ! Here a barrier is used to separate the two program states.
 35:   PetscCallMPIA(MPI_Barrier(PETSC_COMM_WORLD, ierr))

 37:   write (outputString, *) rank, 'Jumbled Hello World\n'
 38:   PetscCallA(PetscPrintf(PETSC_COMM_SELF, outputString, ierr))

 40:   PetscCallA(PetscFinalize(ierr))
 41: end program main

 43: !/*TEST
 44: !
 45: !   test:
 46: !
 47: !TEST*/