[Users] Schedule change in Exact.

[Eloisa Bentivegna]

Erik Schnetter ha scritto:

> I don't think MoL_PseudoEvolution is the right schedule bin for Exact, 
> for two reasons:
> 
> - when thorn Exact is used to evolve, thorn MoL will not be active, 
> hence the bin won't be there

Yes, one would have to have MoL activated anyway in order for this to 
work (which may not have to be ad hoc, as Frank says).

> - as someone (Eloisa?) mentioned, other thorns in MoL_PseudoEvolution 
> assume that the main evolution (providing the spacetime and/or hydro) is 
> done, so that they can access the ADM variables there

But is this actually correct? Roland's example with "BSSNtoADM" being 
naturally scheduled in PseudoEvolution makes it clear that there are at 
least two levels of pseudo-evolution: one that translates the 
gravitational/hydro variables between all the different formulations one 
may need, and a later one where these variables (cast in whichever 
formulation) are used to build derived objects. Also from Roland's 
comments, I understand that the latter class must remain in 
PseudoEvolution (rather than going in ANALYSIS which I would have found 
more natural) because derivatives calculated in ANALYSIS will be wrong 
at the refinement boundaries (did I get this point right?). Is there a 
way to solve this other problem perhaps?

> The first point could be solved by moving PseudoEvolution to a different 
> thorn, e.g. a driver, or to the flesh itself.

That would be very useful.

> The second point could (and maybe should) be solved by having markers in 
> PseudoEvolution that state when the ADM and/or hydro variables are 
> available, and always schedule your analysis routines with respect to 
> these markers.  (This would mimic SphericalSurface.)

I feel like this should have been what PseudoEvolution was meant to 
accomplish...

> At the moment, I would schedule Exact in EVOL (or PRESTEP).

PRESTEP is what is currently used, and leads to uninitialized points at 
the refinement boundaries (even when using the thorn to set all the ADM 
variables, with MoL not active). I guess EVOL is the next candidate; 
I'll give it a try and post back with the results.

Thanks!
Eloisa