[petsc-users] Is there a way to do row/column scaling of jacobian matrix

[Umut Tabak]

On 04/05/2011 05:58 PM, Gong Ding wrote:
> I known the diagonal scaling. And I will try it tomorrow.
> Thank to slepc, I can monitor the eigen values as an approximation of condition number.
> The original problem as condition number about 1e20, which defeat any iterative solver.
>    
 From personal experience, condition estimates larger than 1e+10 means 
practically singular and it is almost impossible to really decrease that 
to a reasonable number unless you use some specific system information 
which is really really difficult...
And again from personal experience, diagonal scaling is the most naive 
scaling out there(however the first to try if you do now know sth 
better), and it does not bring much on these kinds of ill-conditioned 
systems.

Trying to reformulate the problem seems like a better option to me.

Experts will comment on the above propositions ;)

Good luck.
U.

-- 
If I have a thousand ideas and only one turns out to be good,
I am satisfied.
Alfred Nobel