[Users] MoL_InitialCopy

[Roland Haas]

Hello Steve,

> MoL_InitialCopy seems to be a wasted step. It would not be needed if
> (1) time levels were rotated at the end of the iteration loop, or
> (2) we computed B_RHS = Foo(B_p)
> 
> Am I missing something? Why do we do things that way?
(2) is not possible since the RK type methods evaluate the RHS multiple
times and only the first time would be B_RHS = Foo(B_p) and the others
would be B_RHS = Foo(B_intermediate_step).

(1) I don't understand. Right now timelevels are rotated just before
CCTK_PRESTEP which is (from MoL's point of view) identical to rotating
after CCTK_POSTSTEP as far as I understand things.

Having said that: the initialcopy is wasteful. I think there is a
parameter to MoL that would compute the RHS for the next step at the
end of the current iteration which would make B_RHS = Foo(B_p)
unnecessary though it requires that RHS to be permanent so they are no
longer just vehicles to transfer the RHS data to MoL.

Yours,
Roland

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