Actual source code: ex46.cxx
2: static char help[] = "Demonstrates calling Trilinos and then PETSc in the same program.\n\n";
4: /*
5: Example obtained from: http://trilinos.org/docs/dev/packages/tpetra/doc/html/Tpetra_Lesson01.html
6: */
8: #include <petscsys.h>
9: #include <Tpetra_DefaultPlatform.hpp>
10: #include <Tpetra_Version.hpp>
11: #include <Teuchos_GlobalMPISession.hpp> // used if Trilinos is the one that starts up MPI
13: // Do something with the given communicator. In this case, we just
14: // print Tpetra's version to stdout on Process 0 in the given
15: // communicator.
16: void
17: exampleRoutine (const Teuchos::RCP<const Teuchos::Comm<int> >& comm)
18: {
19: if (comm->getRank () == 0) {
20: // On (MPI) Process 0, print out the Tpetra software version.
21: std::cout << Tpetra::version () << std::endl << std::endl;
22: }
23: }
25: int main(int argc,char **argv)
26: {
27: // These "using" declarations make the code more concise, in that
28: // you don't have to write the namespace along with the class or
29: // object name. This is especially helpful with commonly used
30: // things like std::endl.
31: using std::cout;
32: using std::endl;
33: // Start up MPI, if using MPI. Trilinos doesn't have to be built
34: // with MPI; it's called a "serial" build if you build without MPI.
35: // GlobalMPISession hides this implementation detail.
36: //
37: // Note the third argument. If you pass GlobalMPISession the
38: // address of an std::ostream, it will print a one-line status
39: // message with the rank on each MPI process. This may be
40: // undesirable if running with a large number of MPI processes.
41: // You can avoid printing anything here by passing in either
42: // NULL or the address of a Teuchos::oblackholestream.
43: Teuchos::GlobalMPISession mpiSession (&argc, &argv, NULL);
44: // Get a pointer to the communicator object representing
45: // MPI_COMM_WORLD. getDefaultPlatform.getComm() doesn't create a
46: // new object every time you call it; it just returns the same
47: // communicator each time. Thus, you can call it anywhere and get
48: // the same communicator. (This is handy if you don't want to pass
49: // a communicator around everywhere, though it's always better to
50: // parameterize your algorithms on the communicator.)
51: //
52: // "Tpetra::DefaultPlatform" knows whether or not we built with MPI
53: // support. If we didn't build with MPI, we'll get a "communicator"
54: // with size 1, whose only process has rank 0.
55: Teuchos::RCP<const Teuchos::Comm<int> > comm = Tpetra::DefaultPlatform::getDefaultPlatform ().getComm ();
57: PetscInitialize(&argc,&argv,(char*)0,help);
59: // Get my process' rank, and the total number of processes.
60: // Equivalent to MPI_Comm_rank resp. MPI_Comm_size.
61: const int myRank = comm->getRank ();
62: const int size = comm->getSize ();
63: if (myRank == 0) {
64: cout << "Total number of processes: " << size << endl;
65: }
66: // Do something with the new communicator.
67: exampleRoutine (comm);
68: // This tells the Trilinos test framework that the test passed.
69: if (myRank == 0) {
70: cout << "End Result: TEST PASSED" << endl;
71: }
72: // GlobalMPISession calls MPI_Finalize() in its destructor, if
73: // appropriate. You don't have to do anything here! Just return
74: // from main(). Isn't that helpful?
75: PetscFinalize();
76: return 0;
77: }
79: /*TEST
81: build:
82: requires: trilinos
84: test:
85: nsize: 3
86: filter: grep -v "Tpetra in Trilinos"
88: TEST*/