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 exampleRoutine(const Teuchos::RCP<const Teuchos::Comm<int>> &comm)
17: {
18: if (comm->getRank() == 0) {
19: // On (MPI) Process 0, print out the Tpetra software version.
20: std::cout << Tpetra::version() << std::endl << std::endl;
21: }
22: }
24: int main(int argc, char **argv)
25: {
26: // These "using" declarations make the code more concise, in that
27: // you don't have to write the namespace along with the class or
28: // object name. This is especially helpful with commonly used
29: // things like std::endl.
30: using std::cout;
31: using std::endl;
32: // Start up MPI, if using MPI. Trilinos doesn't have to be built
33: // with MPI; it's called a "serial" build if you build without MPI.
34: // GlobalMPISession hides this implementation detail.
35: //
36: // Note the third argument. If you pass GlobalMPISession the
37: // address of an std::ostream, it will print a one-line status
38: // message with the rank on each MPI process. This may be
39: // undesirable if running with a large number of MPI ranks.
40: // You can avoid printing anything here by passing in either
41: // NULL or the address of a Teuchos::oblackholestream.
42: Teuchos::GlobalMPISession mpiSession(&argc, &argv, NULL);
43: // Get a pointer to the communicator object representing
44: // MPI_COMM_WORLD. getDefaultPlatform.getComm() doesn't create a
45: // new object every time you call it; it just returns the same
46: // communicator each time. Thus, you can call it anywhere and get
47: // the same communicator. (This is handy if you don't want to pass
48: // a communicator around everywhere, though it's always better to
49: // parameterize your algorithms on the communicator.)
50: //
51: // "Tpetra::DefaultPlatform" knows whether or not we built with MPI
52: // support. If we didn't build with MPI, we'll get a "communicator"
53: // with size 1, whose only process has rank 0.
54: 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) cout << "Total number of processes: " << size << endl;
64: // Do something with the new communicator.
65: exampleRoutine(comm);
66: // This tells the Trilinos test framework that the test passed.
67: if (myRank == 0) cout << "End Result: TEST PASSED" << endl;
68: // GlobalMPISession calls MPI_Finalize() in its destructor, if
69: // appropriate. You don't have to do anything here! Just return
70: // from main(). Isn't that helpful?
71: PetscFinalize();
72: return 0;
73: }
75: /*TEST
77: build:
78: requires: trilinos
80: test:
81: nsize: 3
82: filter: grep -v "Tpetra in Trilinos"
84: TEST*/