// @HEADER // *********************************************************************** // // Didasko Tutorial Package // Copyright (2005) Sandia Corporation // // Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive // license for use of this work by or on behalf of the U.S. Government. // // This library is free software; you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as // published by the Free Software Foundation; either version 2.1 of the // License, or (at your option) any later version. // // This library is distributed in the hope that it will be useful, but // WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public // License along with this library; if not, write to the Free Software // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 // USA // // Questions about Didasko? Contact Marzio Sala (marzio.sala _AT_ gmail.com) // // *********************************************************************** // @HEADER // this example creates a tridiagonal matrix of type // // | 2 -1 | // | -1 2 -1 | // A = | ... ... ... | // | -1 2 | #include "Didasko_ConfigDefs.h" #if defined(HAVE_DIDASKO_EPETRA) #include "Epetra_ConfigDefs.h" #ifdef HAVE_MPI #include "mpi.h" #include "Epetra_MpiComm.h" #else #include "Epetra_SerialComm.h" #endif #include "Epetra_Map.h" #include "Epetra_Vector.h" #include "Epetra_CrsMatrix.h" int main(int argc, char *argv[]) { #ifdef HAVE_MPI MPI_Init(&argc, &argv); Epetra_MpiComm Comm(MPI_COMM_WORLD); #else Epetra_SerialComm Comm; #endif // set global dimension of the matrix to 5, could be any number int NumGlobalElements = 5; // create a map Epetra_Map Map(NumGlobalElements,0,Comm); // local number of rows int NumMyElements = Map.NumMyElements(); // get update list int * MyGlobalElements = Map.MyGlobalElements( ); // Create an integer vector NumNz that is used to build the Petra Matrix. // NumNz[i] is the Number of OFF-DIAGONAL term for the ith global equation // on this processor int * NumNz = new int[NumMyElements]; // We are building a tridiagonal matrix where each row has (-1 2 -1) // So we need 2 off-diagonal terms (except for the first and last equation) for ( int i=0; i<NumMyElements; i++) if (MyGlobalElements[i]==0 || MyGlobalElements[i] == NumGlobalElements-1) NumNz[i] = 2; else NumNz[i] = 3; // Create a Epetra_Matrix Epetra_CrsMatrix A(Copy,Map,NumNz); // (NOTE: constructor `Epetra_CrsMatrix A(Copy,Map,3);' was ok too.) // Add rows one-at-a-time // Need some vectors to help // Off diagonal Values will always be -1, diagonal term 2 double *Values = new double[2]; Values[0] = -1.0; Values[1] = -1.0; int *Indices = new int[2]; double two = 2.0; int NumEntries; for( int i=0 ; i<NumMyElements; ++i ) { if (MyGlobalElements[i]==0) { Indices[0] = 1; NumEntries = 1; } else if (MyGlobalElements[i] == NumGlobalElements-1) { Indices[0] = NumGlobalElements-2; NumEntries = 1; } else { Indices[0] = MyGlobalElements[i]-1; Indices[1] = MyGlobalElements[i]+1; NumEntries = 2; } A.InsertGlobalValues(MyGlobalElements[i], NumEntries, Values, Indices); // Put in the diagonal entry A.InsertGlobalValues(MyGlobalElements[i], 1, &two, MyGlobalElements+i); } // Finish up, trasforming the matrix entries into local numbering, // to optimize data transfert during matrix-vector products A.FillComplete(); // build up two distributed vectors q and z, and compute // q = A * z Epetra_Vector q(A.RowMap()); Epetra_Vector z(A.RowMap()); // Fill z with 1's z.PutScalar( 1.0 ); A.Multiply(false, z, q); // Compute q = A*z double dotProduct; z.Dot( q, &dotProduct ); if( Comm.MyPID() == 0 ) cout << "q dot z = " << dotProduct << endl; #ifdef HAVE_MPI MPI_Finalize(); #endif delete NumNz; return( EXIT_SUCCESS ); } /* main */ #else #include <stdlib.h> #include <stdio.h> int main(int argc, char *argv[]) { puts("Please configure Didasko with:\n" "--enable-epetra"); return 0; } #endif