"PrecursorAction.C" precursor scaling not applied about moltres HOT 5 CLOSED

I may have misunderstood the purpose of prec_scale.

I simply wanted to apply a scaling factor in the Variables definition in PrecursorAction. This is easily applied by typing "scaling = 1e6" for example when initializing PrecursorAction.

It appears as though prec_scale does not do anything.

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Thanks for your help @gridley
I think "scaling = 1e6" affects the numerical technique that you mentioned (and convergence?), and I've already implemented it.

It appears that "prec_scale" is an input parameter for PrecursorSource and PrecursorDecay kernels.

Anyway, I've (probably) solved my convergence/precision issue by applying "scaling".

I'll close this issue soon, but maybe wait for Alex to give confirmation that we're right, so that we don't confuse future users.

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It indeed doesn't appear that prec_scale is applied anywhere in the action. It looks like it could be used and applied when creating the PrecursorSource and PrecursorDecay kernels. The doc string in the action definitely appears to be wrong...it should read "The amount by which to scale precursors". Anyway I think the thought behind those parameters was potentially for unit scaling, whose goal is generally multiple in a multi-physics setting:

1. Get all initial residuals for all variables in the same neighborhood as each other so that when the non-linear solve is finished you're guaranteed to have convergence in each variable
2. Produce an optimally conditioned jacobian matrix. The closer "important" Jacobian entries are to each other for different variables, then the better conditioned your matrix will be and the better an iterative solver will perform

The scaling parameter in the Variables block is a bit of a dull tool that can definitely help achieve both goals. Since the documentation of the manual scaling parameters I introduced seems a bit lacking and since at first glance I don't see it doing much different than the Variables block scaling parameter, they can probably be deprecated/removed.

I'm going to be taking a back seat, and letting you guys do the Moltres development. However, if you ever want my opinion/thought on something you can definitely tag me.

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Thank you for the clarification. I'll close this issue now.

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