[petsc-users] Quasi newton

[Pierre Seize]

Hi,

If I may, is this what you want ?

https://petsc.org/main/docs/manualpages/SNES/SNESSetLagJacobian.html

Pierre

On 03/05/2022 06:21, Tang, Qi wrote:
> Hi,
> Our code uses FDcoloring to compute Jacobian. The log file indicates most of time is spent in evaluating residual (2600 times in one Newton solve) while it only needs 3 nonlinear iterations and 6 total linear iterations thanks to the fieldsplit pc.
>
> As a temporary solution, is it possible to evaluate Jacobian only once in one Newton solve? This should work well based on my other experience if pc is very efficient. But I cannot find such a flag.
>
> Is there any other solution, other than implementing the analytical Jacobian?
>
> Thanks,
> Qi