Date: 2013-07-02T14:44:00+00:00

Actual source code: ex28.c
petsc-3.4.2 2013-07-02

      2: static char help[] = "Tests MatReorderForNonzeroDiagonal()\n\n";

      4: #include <petscmat.h>

      8: int main(int argc,char **args)
      9: {
     10:   Mat            A,LU;
     11:   Vec            x,y;
     12:   PetscInt       nnz[4]={2,1,1,1},col[4],i;
     14:   PetscScalar    values[4];
     15:   IS             rowperm,colperm;

     17:   PetscInitialize(&argc,&args,(char*)0,help);

     19:   MatCreateSeqAIJ(PETSC_COMM_WORLD,4,4,2,nnz,&A);

     21:   /* build test matrix */
     22:   values[0]=1.0;values[1]=-1.0;
     23:   col[0]   =0;col[1]=2; i=0;
     24:   MatSetValues(A,1,&i,2,col,values,INSERT_VALUES);
     25:   values[0]=1.0;
     26:   col[0]   =1;i=1;
     27:   MatSetValues(A,1,&i,1,col,values,INSERT_VALUES);
     28:   values[0]=-1.0;
     29:   col[0]   =3;i=2;
     30:   MatSetValues(A,1,&i,1,col,values,INSERT_VALUES);
     31:   values[0]=1.0;
     32:   col[0]   =2;i=3;

     34:   MatSetValues(A,1,&i,1,col,values,INSERT_VALUES);
     35:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
     36:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
     37:   MatView(A,PETSC_VIEWER_STDOUT_SELF);

     39:   MatGetOrdering(A,MATORDERINGNATURAL,&rowperm,&colperm);
     40:   MatReorderForNonzeroDiagonal(A,1.e-12,rowperm,colperm);
     41:   PetscPrintf(PETSC_COMM_SELF,"column and row perms\n");
     42:   ISView(rowperm,0);
     43:   ISView(colperm,0);
     44:   MatGetFactor(A,MATSOLVERPETSC,MAT_FACTOR_LU,&LU);
     45:   MatLUFactorSymbolic(LU,A,rowperm,colperm,NULL);
     46:   MatLUFactorNumeric(LU,A,NULL);
     47:   MatView(LU,PETSC_VIEWER_STDOUT_SELF);
     48:   VecCreate(PETSC_COMM_WORLD,&x);
     49:   VecSetSizes(x,PETSC_DECIDE,4);
     50:   VecSetFromOptions(x);
     51:   VecDuplicate(x,&y);

     53:   values[0]=0;values[1]=1.0;values[2]=-1.0;values[3]=1.0;
     54:   for (i=0; i<4; i++) col[i]=i;
     55:   VecSetValues(x,4,col,values,INSERT_VALUES);
     56:   VecAssemblyBegin(x);
     57:   VecAssemblyEnd(x);
     58:   VecView(x,PETSC_VIEWER_STDOUT_SELF);

     60:   MatSolve(LU,x,y);
     61:   VecView(y,PETSC_VIEWER_STDOUT_SELF);

     63:   ISDestroy(&rowperm);
     64:   ISDestroy(&colperm);
     65:   MatDestroy(&LU);
     66:   MatDestroy(&A);
     67:   VecDestroy(&x);
     68:   VecDestroy(&y);
     69:   PetscFinalize();
     70:   return 0;
     71: }