1 static char help[] = "Demonstrates calling Trilinos and then PETSc in the same program.\n\n"; 2 3 /* 4 Example obtained from: http://trilinos.org/docs/dev/packages/tpetra/doc/html/Tpetra_Lesson01.html 5 */ 6 7 #include <petscsys.h> 8 #include <Tpetra_DefaultPlatform.hpp> 9 #include <Tpetra_Version.hpp> 10 #include <Teuchos_GlobalMPISession.hpp> // used if Trilinos is the one that starts up MPI 11 12 // Do something with the given communicator. In this case, we just 13 // print Tpetra's version to stdout on Process 0 in the given 14 // communicator. 15 void exampleRoutine(const Teuchos::RCP<const Teuchos::Comm<int>> &comm) 16 { 17 if (comm->getRank() == 0) { 18 // On (MPI) Process 0, print out the Tpetra software version. 19 std::cout << Tpetra::version() << std::endl << std::endl; 20 } 21 } 22 23 int main(int argc, char **argv) 24 { 25 // These "using" declarations make the code more concise, in that 26 // you don't have to write the namespace along with the class or 27 // object name. This is especially helpful with commonly used 28 // things like std::endl. 29 using std::cout; 30 using std::endl; 31 // Start up MPI, if using MPI. Trilinos doesn't have to be built 32 // with MPI; it's called a "serial" build if you build without MPI. 33 // GlobalMPISession hides this implementation detail. 34 // 35 // Note the third argument. If you pass GlobalMPISession the 36 // address of an std::ostream, it will print a one-line status 37 // message with the rank on each MPI process. This may be 38 // undesirable if running with a large number of MPI ranks. 39 // You can avoid printing anything here by passing in either 40 // NULL or the address of a Teuchos::oblackholestream. 41 Teuchos::GlobalMPISession mpiSession(&argc, &argv, NULL); 42 // Get a pointer to the communicator object representing 43 // MPI_COMM_WORLD. getDefaultPlatform.getComm() doesn't create a 44 // new object every time you call it; it just returns the same 45 // communicator each time. Thus, you can call it anywhere and get 46 // the same communicator. (This is handy if you don't want to pass 47 // a communicator around everywhere, though it's always better to 48 // parameterize your algorithms on the communicator.) 49 // 50 // "Tpetra::DefaultPlatform" knows whether or not we built with MPI 51 // support. If we didn't build with MPI, we'll get a "communicator" 52 // with size 1, whose only process has rank 0. 53 Teuchos::RCP<const Teuchos::Comm<int>> comm = Tpetra::DefaultPlatform::getDefaultPlatform().getComm(); 54 55 PetscFunctionBeginUser; 56 PetscCall(PetscInitialize(&argc, &argv, (char *)0, help)); 57 58 // Get my process' rank, and the total number of processes. 59 // Equivalent to MPI_Comm_rank resp. MPI_Comm_size. 60 const int myRank = comm->getRank(); 61 const int size = comm->getSize(); 62 if (myRank == 0) cout << "Total number of processes: " << size << endl; 63 // Do something with the new communicator. 64 exampleRoutine(comm); 65 // This tells the Trilinos test framework that the test passed. 66 if (myRank == 0) cout << "End Result: TEST PASSED" << endl; 67 // GlobalMPISession calls MPI_Finalize() in its destructor, if 68 // appropriate. You don't have to do anything here! Just return 69 // from main(). Isn't that helpful? 70 PetscCall(PetscFinalize()); 71 return 0; 72 } 73 74 /*TEST 75 76 build: 77 requires: trilinos 78 79 test: 80 nsize: 3 81 filter: grep -v "Tpetra in Trilinos" 82 83 TEST*/ 84