1 2 static char help[] = "Demonstrates calling Trilinos and then PETSc in the same program.\n\n"; 3 4 /* 5 Example obtained from: http://trilinos.org/docs/dev/packages/tpetra/doc/html/Tpetra_Lesson01.html 6 */ 7 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 12 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 } 24 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 (); 56 57 PetscCall(PetscInitialize(&argc,&argv,(char*)0,help)); 58 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 PetscCall(PetscFinalize()); 76 return 0; 77 } 78 79 /*TEST 80 81 build: 82 requires: trilinos 83 84 test: 85 nsize: 3 86 filter: grep -v "Tpetra in Trilinos" 87 88 TEST*/ 89