1 2 static char help[] = "Demonstrates calling Trilinos and then PETSc in the same program.\n\n"; 3 4 /*T 5 Concepts: introduction to PETSc^Trilinos 6 Processors: n 7 8 Example obtained from: http://trilinos.org/docs/dev/packages/tpetra/doc/html/Tpetra_Lesson01.html 9 T*/ 10 11 12 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 17 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 } 29 30 int main(int argc,char **argv) 31 { 32 PetscErrorCode ierr; 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 (); 62 63 ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr; 64 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 ierr = PetscFinalize(); 82 return ierr; 83 } 84 85 86 87 88 /*TEST 89 90 build: 91 requires: trilinos 92 93 test: 94 nsize: 3 95 filter: grep -v "Tpetra in Trilinos" 96 97 TEST*/ 98