On 2/14/17 6:53 AM, Matthew Knepley wrote:
Explicit methods use only RHSFunction and ignore IFunction, so in
your case, if you change TS type to rk and ssp at run time, you are
actually solving u_t = G(t,u). If RHSFunction is not provided, PETSc
will assume the RHS is zero (u_t=0).
I do not agree with this. I thought our aim was to support users
comparing explicit with implicit with semi-implicit. This breaks that
model completely.
Matt, all RHSFunction can be turned into IFunction but not the other way
around. Explicit TS solvers cannot deal with all forms of IFunction and
providing support for classifying them may be burdensome and difficult
to scale. I think it's more lucrative to improve the documentation.
Emil
