Actual source code: ex1f.F90

      1: ! Introductory example that illustrates printing: Fortran Example
      2: #include <petsc/finclude/petscsys.h>
      3: program main
      4:   use petscsys

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

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

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

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

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

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

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

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

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

     43:   PetscCallA(PetscFinalize(ierr))

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