[petsc-users] Return value of PCFactorGetMatrix

[Uwe Schlifkowitz]

Dear list,

following advice from this list and petsc documentation (especially http://www.mcs.anl.gov/petsc/petsc-current/src/ksp/ksp/examples/tutorials/ex52.c.html ), i have the following code:

//---------
				ierr = KSPCreate( coml,&kspBA);CHKERRQ(ierr);
				ierr = KSPSetOperators( kspBA, Kt, Kt, DIFFERENT_NONZERO_PATTERN);CHKERRQ(ierr);

				ierr = KSPSetType(kspBA,KSPPREONLY);CHKERRQ(ierr);

				ierr = KSPGetPC(kspBA, &pcba);

				ierr = PCSetType(pcba, PCCHOLESKY);CHKERRQ(ierr);

				ierr = PCFactorSetMatSolverPackage(pcba, MATSOLVERPETSC);CHKERRQ(ierr);
				ierr = PCFactorSetUpMatSolverPackage(pcba);CHKERRQ(ierr);
				ierr = MatGetFactor(Kt,"petsc",MAT_FACTOR_CHOLESKY,&DiagM);CHKERRQ(ierr);
				ierr = PCFactorGetMatrix(pcba, &DiagM);CHKERRQ(ierr);

				ierr = KSPSetUp(kspBA);CHKERRQ(ierr);
				//ierr = MatView(DiagM,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
				//ierr = MatView(DiagM,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
				ierr = VecDuplicate(fin,&diag);CHKERRQ(ierr);
				ierr = MatGetDiagonal(DiagM,diag);CHKERRQ(ierr);
//-----------

where Kt is a stiffness matrix. I was hoping that PCFactorGetMatrix() makes DiagM become D from a LDL^T factorization, but to me it seems as if this is not true.

Can anyone clarify?

Regards,
Uwe