Actual source code: ex30.c

  1: /*$Id: ex30.c,v 1.27 2001/08/07 03:03:07 balay Exp $*/

  3: static char help[] = "Tests ILU factorization and illustrates drawing of matrix sparsity structure with MatView().n
  4:   Input parameters are:n
  5:   -lf <level> : level of fill for ILU (default is 0)n
  6:   -lu : use full LU factorizationn
  7:   -m <value>,-n <value> : grid dimensionsn
  8: Note that most users should employ the SLES interface to then
  9: linear solvers instead of using the factorization routinesn
 10: directly.nn";

 12:  #include petscmat.h

 14: int main(int argc,char **args)
 15: {
 16:   Mat         C,A;
 17:   int         i,j,m = 5,n = 5,I,J,ierr,lf = 0;
 18:   PetscTruth  flg1;
 19:   PetscScalar v;
 20:   IS          row,col;
 21:   PetscViewer viewer1,viewer2;

 23:   PetscInitialize(&argc,&args,(char *)0,help);
 24:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
 25:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
 26:   PetscOptionsGetInt(PETSC_NULL,"-lf",&lf,PETSC_NULL);

 28:   PetscViewerDrawOpen(PETSC_COMM_SELF,0,0,0,0,400,400,&viewer1);
 29:   PetscViewerDrawOpen(PETSC_COMM_SELF,0,0,400,0,400,400,&viewer2);

 31:   MatCreate(PETSC_COMM_SELF,m*n,m*n,m*n,m*n,&C);
 32:   MatSetFromOptions(C);
 33:   MatSeqBDiagSetPreallocation(C,0,1,PETSC_NULL,PETSC_NULL);
 34:   MatSeqAIJSetPreallocation(C,5,PETSC_NULL);

 36:   /* Create the matrix. (This is five-point stencil with some extra elements) */
 37:   for (i=0; i<m; i++) {
 38:     for (j=0; j<n; j++) {
 39:       v = -1.0;  I = j + n*i;
 40:       J = I - n; if (J>=0)  {MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 41:       J = I + n; if (J<m*n) {MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 42:       J = I - 1; if (J>=0)  {MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 43:       J = I + 1; if (J<m*n) {MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 44:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 45:     }
 46:   }
 47:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 48:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 50:   MatGetOrdering(C,MATORDERING_RCM,&row,&col);
 51:   printf("original matrix:n");
 52:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_SELF,PETSC_VIEWER_ASCII_INFO);
 53:   MatView(C,PETSC_VIEWER_STDOUT_SELF);
 54:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_SELF);
 55:   MatView(C,PETSC_VIEWER_STDOUT_SELF);
 56:   MatView(C,viewer1);

 58:   /* Compute factorization */
 59:   PetscOptionsHasName(PETSC_NULL,"-lu",&flg1);
 60:   if (flg1){
 61:     MatLUFactorSymbolic(C,row,col,PETSC_NULL,&A);
 62:   } else {
 63:     MatILUInfo info;
 64:     info.levels        = lf;
 65:     info.fill          = 1.0;
 66:     info.diagonal_fill = 0;
 67:     info.damping       = 0;
 68:     info.damp          = 0;
 69:     info.zeropivot     = 0.0;
 70:     MatILUFactorSymbolic(C,row,col,&info,&A);
 71:   }
 72:   MatLUFactorNumeric(C,&A);

 74:   printf("factored matrix:n");
 75:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_SELF,PETSC_VIEWER_ASCII_INFO);
 76:   MatView(A,PETSC_VIEWER_STDOUT_SELF);
 77:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_SELF);
 78:   MatView(A,PETSC_VIEWER_STDOUT_SELF);
 79:   MatView(A,viewer2);

 81:   /* Free data structures */
 82:   MatDestroy(C);
 83:   MatDestroy(A);
 84:   ISDestroy(row);
 85:   ISDestroy(col);
 86:   PetscViewerDestroy(viewer1);
 87:   PetscViewerDestroy(viewer2);
 88:   PetscFinalize();
 89:   return 0;
 90: }