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*/