[petsc-users] Quasi newton

[Tang, Qi]

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