1: ! Synchronized printing: Fortran Example
  2: 
  3: 
  4: program main
  5: #include <petsc/finclude/petscsys.h> 
  6:       use petscsys
  7:       
  8:       implicit none
  9:       PetscErrorCode    :: ierr
 10:       PetscMPIInt       :: myRank,mySize
 11:       character(len=80) :: outputString
 12:       
 13:       ! Every PETSc program should begin with the PetscInitialize() routine.
 14:       
 15:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
 16:       if (ierr /= 0) then
 17:         write(6,*) 'Unable to initialize PETSc'
 18:         stop
 19:       endif
 20:       
 21:       ! The following MPI calls return the number of processes 
 22:       ! being used and the rank of this process in the group
 23:       
 24:       call MPI_Comm_size(MPI_COMM_WORLD,mySize,ierr)
 25:       CHKERRA(ierr)
 26:       call MPI_Comm_rank(MPI_COMM_WORLD,myRank,ierr)
 27:       CHKERRA(ierr)
 28:       
 29:       ! Here we would like to print only one message that represents
 30:       ! all the processes in the group
 31:       write(outputString,*) 'No of Processors = ', mysize, ', rank = ',myRank,'\n'
 32:       call PetscPrintf(PETSC_COMM_WORLD,outputString,ierr)
 33:       CHKERRA(ierr)
 34:       
 35:       write(outputString,*) myRank,'Synchronized Hello World\n'
 36:       call PetscSynchronizedPrintf(PETSC_COMM_WORLD,outputString,ierr)
 37:       CHKERRA(ierr)
 38:       write(outputString,*) myRank,'Synchronized Hello World - Part II\n'
 39:       call PetscSynchronizedPrintf(PETSC_COMM_WORLD,outputString,ierr)
 40:       CHKERRA(ierr)
 41:       call PetscSynchronizedFlush(PETSC_COMM_WORLD,PETSC_STDOUT,ierr)
 42:       CHKERRA(ierr)
 43:       
 44:       ! Here a barrier is used to separate the two program states.
 45:       call MPI_Barrier(PETSC_COMM_WORLD,ierr)
 46:       CHKERRA(ierr)
 47:       
 48:       write(outputString,*) myRank,'Jumbled Hello World\n'
 49:       call PetscPrintf(PETSC_COMM_SELF,outputString,ierr)
 50:       CHKERRA(ierr)
 51:       
 52:       call PetscFinalize(ierr)
 53:       CHKERRA(ierr)
 54:       
 55: end program main