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ReduceAllAndScatter_test.cpp
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00004 //                    Teuchos: Common Tools Package
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00041 
00042 #include "Teuchos_ConfigDefs.hpp"
00043 #include "Teuchos_DefaultComm.hpp"
00044 #include "Teuchos_CommHelpers.hpp"
00045 #include "Teuchos_GlobalMPISession.hpp"
00046 
00047 int main(int argc, char* argv[]) {
00048 
00049   using Teuchos::RCP;
00050 
00051   Teuchos::GlobalMPISession mpiSession(&argc, &argv);
00052 
00053   int ierr = 0;
00054 
00055   RCP<const Teuchos::Comm<int> >
00056     comm = Teuchos::DefaultComm<int>::getComm();
00057 
00058   const int size = Teuchos::size(*comm);
00059   const int rank = Teuchos::rank(*comm);
00060 
00061   if (rank == 0) {
00062     std::cout
00063       << "Rank: " << rank 
00064       << "\t\tSize: " << size << std::endl;
00065   }
00066 
00067   const int one  = Teuchos::OrdinalTraits<int>::one();
00068 
00069   std::vector<int> sendbuf(size,one);
00070   std::vector<int> recvcounts(size,one);
00071 
00072   // Try straight MPI version
00073 #ifdef HAVE_MPI
00074   {
00075     std::vector<int> sbuf(sendbuf);
00076     std::vector<int> rcnt(recvcounts);
00077     int rbuf;
00078 
00079     MPI_Comm mpi_comm = MPI_COMM_WORLD;
00080     MPI_Reduce_scatter(&sbuf[0],&rbuf,&rcnt[0],MPI_INT,MPI_SUM,mpi_comm);
00081 
00082     // should be size
00083     if (rank == 0) {
00084       std::cout << "Received from direct MPI call: " << rbuf << std::endl;
00085     }
00086     ierr += (rbuf == size ? 0 : 1);
00087   }
00088 #endif
00089 
00090   // Try straight MPI version with user-defined type
00091 #ifdef HAVE_MPI
00092   {
00093     std::vector<int> sbuf(sendbuf);
00094     std::vector<int> rcnt(recvcounts);
00095     int rbuf;
00096 
00097     MPI_Comm mpi_comm = MPI_COMM_WORLD;
00098     MPI_Datatype _chars_type;
00099     MPI_Type_contiguous(sizeof(int), MPI_CHAR, &_chars_type);
00100     MPI_Reduce_scatter(&sbuf[0], &rbuf, &rcnt[0], _chars_type, MPI_SUM, mpi_comm);
00101 
00102     // should be size
00103     if (rank == 0) {
00104       std::cout << "Received from direct MPI call with user type: " << rbuf << std::endl;
00105     }
00106     ierr += (rbuf == size ? 0 : 1);
00107   }
00108 #endif
00109 
00110   // Try Teuchos version
00111   { 
00112     std::vector<int> sbuf(sendbuf);
00113     std::vector<int> rcnt(recvcounts);
00114     int rbuf;
00115 
00116     Teuchos::reduceAllAndScatter<int>(*comm,Teuchos::REDUCE_SUM,(int)sbuf.size(),&sbuf[0],&rcnt[0],&rbuf);
00117 
00118     // should be size
00119     if (rank == 0) {
00120       std::cout << "Received from MPI-via-Teuchos call: " << rbuf << std::endl;
00121     }
00122     ierr += (rbuf == size ? 0 : 1);
00123   }
00124 
00125   if (rank == 0) {
00126     if (ierr) {
00127       std::cerr << "Test FAILED." << std::endl;
00128     }
00129     else {
00130       std::cerr << "Test passed." << std::endl;
00131     }
00132   }
00133   return ierr;
00134 }
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