On Oct 22, 2013, at 11:58 AM, Jed Brown <[email protected]> wrote:
> Barry Smith <[email protected]> writes: > >> Begin forwarded message: >> >>> From: Christophe Ortiz <[email protected]> >>> >>> [0]PETSC ERROR: ! >>> [0]PETSC ERROR: TSStep has failed due to DIVERGED_NONLINEAR_SOLVE, increase >>> -ts_max_snes_failures or make negative to attempt recovery! >>> >> >> Do we really want this as a our "helpful message" here? Usually the >> problem is a bad Jacobian etc which the person needs to track >> down. It would be better if this instead listed an FAQ question >> with information (and links there) to all possible causes of the >> problem and how to track it down. Just allowing failure here is >> not the first step one should take I think. > > Hmm, this is not uncommon if solving a strongly nonlinear problem, > especially when using crude error tolerance. So for the expert user, > this error is usually offering the right guidance. What expert users do we have ? 90+% of all failures of Newton are due to bad Jacobians so the suggestion here is useful less than 10% of the time and sends all non-experts down the wrong road. BTW: we need to finish up the refactorization of -snes_type test to the continuous test that runs for all solves. We have two competing fragments that need merging. Barry > To accommodate the > error-prone user, it would be fine to use a link to a web page > explaining the steps to debug.
