[petsc-users] PCComposite

[Hui Zhang]

On May 28, 2012, at 5:29 PM, Jed Brown wrote:

> On Mon, May 28, 2012 at 10:25 AM, Hui Zhang <mike.hui.zhang at hotmail.com> wrote:
> But I'm not *changing* the operator. It is PCSetUp_Composite that call PCSetOperators on sub pc
> a second time-- he does not know that the sub pc has been set up before.
> 
> Why do you call PCSetUp the first time?

Because the PCComposite has two subpc's and one of the subpc is needed to be set up and used for 
construction of the other subpc.

> 
> We don't currently have a mechanism to automatically know whether the operator has changed since the last setup, that's what the flag argument is for.

Yes, I found this is a feasible way.  I just set SAME_PRECONDITIONER for the PCComposite. 
It is fine to me.  Thanks!

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