Actual source code: ex2f.F90

petsc-main 2021-03-03
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  1: ! Synchronized printing: Fortran Example


  4: program main
  5: #include <petsc/finclude/petscsys.h>
  6:       use petscsys

  8:       implicit none
  9:       PetscErrorCode                    :: ierr
 10:       PetscMPIInt                       :: myRank,mySize
 11:       character(len=PETSC_MAX_PATH_LEN) :: outputString

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

 15:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
 16:       if (ierr /= 0) then
 17:         write(6,*) 'Unable to initialize PETSc'
 18:         stop
 19:       endif

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

 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)

 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)

 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)

 44:       ! Here a barrier is used to separate the two program states.
 45:       call MPI_Barrier(PETSC_COMM_WORLD,ierr)
 46:       CHKERRA(ierr)

 48:       write(outputString,*) myRank,'Jumbled Hello World\n'
 49:       call PetscPrintf(PETSC_COMM_SELF,outputString,ierr)
 50:       CHKERRA(ierr)

 52:       call PetscFinalize(ierr)
 53:       CHKERRA(ierr)

 55: end program main

 57: !/*TEST
 58: !
 59: !   test:
 60: !
 61: !TEST*/