Actual source code: ex1f.F90

  1: ! Introductory example that illustrates printing: Fortran Example

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

  7:   implicit none
  8:   PetscErrorCode    :: ierr
  9:   PetscMPIInt       :: rank, size
 10:   character(len=80) :: outputString

 12:   ! Every PETSc routine should begin with the PetscInitialize() routine.
 13:   PetscCallA(PetscInitialize(ierr))

 15:   ! We can now change the communicator universe for PETSc
 16:   PetscCallMPIA(MPI_Comm_size(PETSC_COMM_WORLD, size, ierr))
 17:   PetscCallMPIA(MPI_Comm_rank(PETSC_COMM_WORLD, rank, ierr))

 19:   ! Here we would like to print only one message that represents all the processes in the group
 20:   ! We use PetscPrintf() with the
 21:   ! communicator PETSC_COMM_WORLD.  Thus, only one message is
 22:   ! printed representng PETSC_COMM_WORLD, i.e., all the processors.

 24:   write (outputString, *) 'No of Processors = ', size, ', rank = ', rank, '\n'
 25:   PetscCallA(PetscPrintf(PETSC_COMM_WORLD, outputString, ierr))

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

 30:   ! Here we simply use PetscPrintf() with the communicator PETSC_COMM_SELF,
 31:   ! where each process is considered separately and prints independently
 32:   ! to the screen.  Thus, the output from different processes does not
 33:   ! appear in any particular order.

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

 38:   ! Always call PetscFinalize() before exiting a program.  This routine
 39:   ! - finalizes the PETSc libraries as well as MPI
 40:   ! - provides summary and diagnostic information if certain runtime
 41:   !   options are chosen (e.g., -log_view).  See PetscFinalize()
 42:   !  manpage for more information.

 44:   PetscCallA(PetscFinalize(ierr))

 46: end program main
 47: !/*TEST
 48: !
 49: !   test:
 50: !
 51: !TEST*/