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

 38:   MatGetOrdering(A,MATORDERING_NATURAL,&rowperm,&colperm);
 39:   MatReorderForNonzeroDiagonal(A,1.e-12,rowperm,colperm);
 40:   PetscPrintf(PETSC_COMM_SELF,"column and row perms\n");
 41:   ISView(rowperm,0);
 42:   ISView(colperm,0);
 43:   MatLUFactorSymbolic(A,rowperm,colperm,PETSC_NULL,&LU);
 44:   MatLUFactorNumeric(A,PETSC_NULL,&LU);
 45:   MatView(LU,PETSC_VIEWER_STDOUT_SELF);
 46:   VecCreate(PETSC_COMM_WORLD,&x);
 47:   VecSetSizes(x,PETSC_DECIDE,4);
 48:   VecSetFromOptions(x);
 49:   VecDuplicate(x,&y);
 50:   values[0]=0;values[1]=1.0;values[2]=-1.0;values[3]=1.0;
 51:   for (i=0; i<4; i++) col[i]=i;
 52:   VecSetValues(x,4,col,values,INSERT_VALUES);
 53:   VecAssemblyBegin(x);
 54:   VecAssemblyEnd(x);
 55:   VecView(x,PETSC_VIEWER_STDOUT_SELF);

 57:   MatSolve(LU,x,y);
 58:   VecView(y,PETSC_VIEWER_STDOUT_SELF);

 60:   ISDestroy(rowperm);
 61:   ISDestroy(colperm);
 62:   MatDestroy(LU);
 63:   MatDestroy(A);
 64:   VecDestroy(x);
 65:   VecDestroy(y);
 66:   PetscFinalize();
 67:   return 0;
 68: }