[petsc-users] How to set L1 norm as the converge test?

[Brian Yang]

Thanks Mat and Barry,

Yes I want to use the L1 norm in the convergence test. For the ||Ax-b||, I
always want to calculate L1 norm instead of L2. Is Mat's way gonna work on
this?

On Wed, Sep 24, 2014 at 2:17 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Brian,
>
>    Do you wish to monitor the convergence of the L1 norm, or do you wish
> to use the L1 norm in the convergence test?   Regardless you cannot change
> the LSQR or CG to be a different algorithm (with different convergence
> properties) with the L1 norm.
>
>
>   Barry
>
> On Sep 24, 2014, at 2:08 PM, Brian Yang <brianyang1106 at gmail.com> wrote:
>
> > Hi all,
> >
> > For example, I am using LSQR or CG to solve Ax=b.
> >
> > When we turn on the monitor option of solving the linear system, we
> could see iteration number and residual for each iteration. I believe it's
> L2 norm of the objective function?
> >
> > If yes, is there a way that I could set it to L1 norm for solving the
> system?
> >
> > Thanks.
> >
> > --
> > Brian Yang
> > U of Houston
> >
> >
> >
>
>


-- 
Brian Yang
U of Houston
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