[petsc-users] SNES residual and unknown scaling

[Jed Brown]

anton <popov at uni-mainz.de> writes:

> Hi,
>
> Applying -snes_mf_operator to a Stokes problem is quite sensitive to 
> scaling of the velocity and pressure unknown (residual) blocks.
> Apart from high-level scaling of the entire problem (which we already 
> have), it would be also nice to have a sort of low-level scaling 
> directly in SNES.
> Can someone suggest how it can be best implemented (or probably already 
> implemented) in PETSc.

How would you foresee this working?  How would you like to decide on
scaling parameters?  Preconditioned or unpreconditioned norm?  Automatic
scaling is a tricky business.
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