Actual source code: ex46.cxx
petsc-3.12.4 2020-02-04
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      2: static char help[] = "Demonstrates calling Trilinos and then PETSc in the same program.\n\n";

      4: /*T
      5:    Concepts: introduction to PETSc^Trilinos
      6:    Processors: n

      8:    Example obtained from: http://trilinos.org/docs/dev/packages/tpetra/doc/html/Tpetra_Lesson01.html
      9: T*/

     13:  #include <petscsys.h>
     14: #include <Tpetra_DefaultPlatform.hpp>
     15: #include <Tpetra_Version.hpp>
     16: #include <Teuchos_GlobalMPISession.hpp>    // used if Trilinos is the one that starts up MPI

     18: // Do something with the given communicator.  In this case, we just
     19: // print Tpetra's version to stdout on Process 0 in the given
     20: // communicator.
     21: void
     22: exampleRoutine (const Teuchos::RCP<const Teuchos::Comm<int> >& comm)
     23: {
     24:   if (comm->getRank () == 0) {
     25:     // On (MPI) Process 0, print out the Tpetra software version.
     26:     std::cout << Tpetra::version () << std::endl << std::endl;
     27:   }
     28: }

     30: int main(int argc,char **argv)
     31: {
     33:   // These "using" declarations make the code more concise, in that
     34:   // you don't have to write the namespace along with the class or
     35:   // object name.  This is especially helpful with commonly used
     36:   // things like std::endl.
     37:   using std::cout;
     38:   using std::endl;
     39:   // Start up MPI, if using MPI.  Trilinos doesn't have to be built
     40:   // with MPI; it's called a "serial" build if you build without MPI.
     41:   // GlobalMPISession hides this implementation detail.
     42:   //
     43:   // Note the third argument.  If you pass GlobalMPISession the
     44:   // address of an std::ostream, it will print a one-line status
     45:   // message with the rank on each MPI process.  This may be
     46:   // undesirable if running with a large number of MPI processes.
     47:   // You can avoid printing anything here by passing in either
     48:   // NULL or the address of a Teuchos::oblackholestream.
     49:   Teuchos::GlobalMPISession mpiSession (&argc, &argv, NULL);
     50:   // Get a pointer to the communicator object representing
     51:   // MPI_COMM_WORLD.  getDefaultPlatform.getComm() doesn't create a
     52:   // new object every time you call it; it just returns the same
     53:   // communicator each time.  Thus, you can call it anywhere and get
     54:   // the same communicator.  (This is handy if you don't want to pass
     55:   // a communicator around everywhere, though it's always better to
     56:   // parameterize your algorithms on the communicator.)
     57:   //
     58:   // "Tpetra::DefaultPlatform" knows whether or not we built with MPI
     59:   // support.  If we didn't build with MPI, we'll get a "communicator"
     60:   // with size 1, whose only process has rank 0.
     61:   Teuchos::RCP<const Teuchos::Comm<int> > comm = Tpetra::DefaultPlatform::getDefaultPlatform ().getComm ();

     63:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;

     65:   // Get my process' rank, and the total number of processes.
     66:   // Equivalent to MPI_Comm_rank resp. MPI_Comm_size.
     67:   const int myRank = comm->getRank ();
     68:   const int size = comm->getSize ();
     69:   if (myRank == 0) {
     70:     cout << "Total number of processes: " << size << endl;
     71:   }
     72:   // Do something with the new communicator.
     73:   exampleRoutine (comm);
     74:   // This tells the Trilinos test framework that the test passed.
     75:   if (myRank == 0) {
     76:     cout << "End Result: TEST PASSED" << endl;
     77:   }
     78:   // GlobalMPISession calls MPI_Finalize() in its destructor, if
     79:   // appropriate.  You don't have to do anything here!  Just return
     80:   // from main().  Isn't that helpful?
     81:   PetscFinalize();
     82:   return ierr;
     83: }

     88: /*TEST

     90:    build:
     91:      requires: trilinos

     93:    test:
     94:       nsize: 3
     95:       filter: grep -v "Tpetra in Trilinos"

     97: TEST*/