Preconditioner for bicg

[Barry Smith]

  You are right. What was Victor thinking? Seems a pretty strange algorithm
in that case. I have updated the manual page yet again to reflect this.

   Barry

I am not sure we really want to have this behavior, seems too likely to 
perform badly.

On Fri, 12 Oct 2007, Lisandro Dalcin wrote:

> But for cgne, looking at the code, ApplyTranspose seems to be optional...
> 
> On 10/11/07, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> > [bsmith:~] bsmith% cd Src/petsc-dev/src/ksp/ksp/impls
> > [bsmith:ksp/ksp/impls] bsmith% grep ApplyTranspose */*.c
> > bicg/bicg.c:  ierr = KSP_PCApplyTranspose(ksp,Rl,Zl);CHKERRQ(ierr);
> > bicg/bicg.c:       ierr = KSP_PCApplyTranspose(ksp,Rl,Zl);CHKERRQ(ierr);
> > bicg/bicg.c:       ierr = KSP_PCApplyTranspose(ksp,Rl,Zl);CHKERRQ(ierr);
> >
> > [bsmith:ksp/ksp/impls] bsmith% grep ApplyTranspose */*/*.c
> > cg/cgne/cgne.c:  ierr = PCApplyTransposeExists(ksp->pc,&transpose_pc);CHKERRQ(ierr);
> > cg/cgne/cgne.c:    ierr = KSP_PCApplyTranspose(ksp,T,Z);CHKERRQ(ierr);
> > cg/cgne/cgne.c:  ierr = KSP_PCApplyTranspose(ksp,T,Z);CHKERRQ(ierr);
> >
> >   These are the two methods that require the transpose operation.
> >
> >   I have documented both of their manual pages to indicate this.
> >
> >    Barry
> >
> >
> > On Thu, 11 Oct 2007, Keita Teranishi wrote:
> >
> > > Hi Barry,
> > >
> > > Could you suggest any other KSP solvers that have the same type of problems?
> > >
> > > Thanks,
> > > ================================
> > >  Keita Teranishi
> > >  Math Software Group
> > >  Cray Inc.
> > >  keita at cray.com
> > > ================================
> > >
> > > -----Original Message-----
> > > From: owner-petsc-users at mcs.anl.gov [mailto:owner-petsc-users at mcs.anl.gov] On Behalf Of Barry Smith
> > > Sent: Thursday, October 11, 2007 4:50 PM
> > > To: petsc-users at mcs.anl.gov
> > > Subject: Re: Preconditioner for bicg
> > >
> > >
> > >   For some preconditioners it is simply not easily possible to apply the
> > > transpose of the preconditioner. Even multigrid requires some work to do this.
> > >
> > >    Barry
> > >
> > >
> > > On Thu, 11 Oct 2007, Keita Teranishi wrote:
> > >
> > > > Hi,
> > > >
> > > >
> > > >
> > > > I'd like to make sure preconditioners supported for bicg. I found bicg only accepts preconditioners that is interfaced through PCApplyTranspose.
> > > >
> > > > For this reason, I see several preconditioners fails with bicg.
> > > >
> > > >
> > > >
> > > > Thanks,
> > > >
> > > > ================================
> > > >  Keita Teranishi
> > > >  Math Software Group
> > > >  Cray Inc.
> > > >  keita at cray.com
> > > > ================================
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
> 
> 
>