Actual source code: ex9.c

  1: /*$Id: ex9.c,v 1.25 2001/09/11 16:32:50 bsmith Exp $*/

  3: static char help[] = "Tests MPI parallel matrix creation.nn";

 5:  #include petscmat.h

  7: int main(int argc,char **args)
  8: {
  9:   Mat          C;
 10:   MatInfo      info;
 11:   int          i,j,m = 3,n = 2,rank,size,low,high,iglobal;
 12:   int          I,J,ierr,ldim;
 13:   PetscTruth   flg;
 14:   PetscScalar  v,one = 1.0;
 15:   Vec          u,b;
 16:   int          bs,ndiag,diag[7];  bs = 1,ndiag = 5;

 18:   PetscInitialize(&argc,&args,(char *)0,help);
 19:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 20:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 21:   n = 2*size;

 23:   MatCreate(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
 24:   MatSetFromOptions(C);

 26:   diag[0] = n;
 27:   diag[1] = 1;
 28:   diag[2] = 0;
 29:   diag[3] = -1;
 30:   diag[4] = -n;
 31:   if (size>1) {ndiag = 7; diag[5] = 2; diag[6] = -2;}
 32:   MatMPIBDiagSetPreallocation(C,ndiag,bs,diag,PETSC_NULL);
 33:   MatMPIAIJSetPreallocation(C,5,PETSC_NULL,5,PETSC_NULL);

 35:   /* Create the matrix for the five point stencil, YET AGAIN */
 36:   for (i=0; i<m; i++) {
 37:     for (j=2*rank; j<2*rank+2; j++) {
 38:       v = -1.0;  I = j + n*i;
 39:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 40:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 41:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 42:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 43:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 44:     }
 45:   }

 47:   /* Add extra elements (to illustrate variants of MatGetInfo) */
 48:   I = n; J = n-2; v = 100.0;
 49:   MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);
 50:   I = n-2; J = n; v = 100.0;
 51:   MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);

 53:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 54:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 56:   /* Form vectors */
 57:   VecCreate(PETSC_COMM_WORLD,&u);
 58:   VecSetSizes(u,PETSC_DECIDE,m*n);
 59:   VecSetFromOptions(u);
 60:   VecDuplicate(u,&b);
 61:   VecGetLocalSize(u,&ldim);
 62:   VecGetOwnershipRange(u,&low,&high);
 63:   for (i=0; i<ldim; i++) {
 64:     iglobal = i + low;
 65:     v = one*((PetscReal)i) + 100.0*rank;
 66:     VecSetValues(u,1,&iglobal,&v,INSERT_VALUES);
 67:   }
 68:   VecAssemblyBegin(u);
 69:   VecAssemblyEnd(u);

 71:   MatMult(C,u,b);

 73:   VecView(u,PETSC_VIEWER_STDOUT_WORLD);
 74:   VecView(b,PETSC_VIEWER_STDOUT_WORLD);

 76:   VecDestroy(u);
 77:   VecDestroy(b);

 79:   PetscOptionsHasName(PETSC_NULL,"-view_info",&flg);
 80:   if (flg)  {PetscViewerSetFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);}
 81:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 83:   MatGetInfo(C,MAT_GLOBAL_SUM,&info);
 84:   PetscPrintf(PETSC_COMM_WORLD,"matrix information (global sums):n
 85:      nonzeros = %d, allocated nonzeros = %dn",(int)info.nz_used,(int)info.nz_allocated);
 86:   MatGetInfo (C,MAT_GLOBAL_MAX,&info);
 87:   PetscPrintf(PETSC_COMM_WORLD,"matrix information (global max):n
 88:      nonzeros = %d, allocated nonzeros = %dn",(int)info.nz_used,(int)info.nz_allocated);

 90:   MatDestroy(C);
 91:   PetscFinalize();
 92:   return 0;
 93: }