[petsc-users] ARKIMEX produces incorrect values

[Jed Brown]

Ed Bueler <elbueler at alaska.edu> writes:

> Darn, sorry.
>
> I realize the ARKIMEX page does say "Methods with an explicit stage can
> only be used with ODE in which the stiff part G(t,X,Xdot) has the form Xdot
> + Ghat(t,X)."  So my example does not do that.  Is there a way for
> ARKIMEX to detect that dG/d(Xdot) = I?

Other than sampling its action on vectors?  Not really; it's user code.

Emil, per our thread the other day, here is an example of "misuse" by a very experienced user.  We need a better way to detect or provide feedback to users.