Modeling Toolkit (v8.76) - Change parameters by reference with remake

[ChrisRackauckas]

@Bill_Holmes

The basic goal is to create and ODEproblem from a MTK model, and then remake the problem with a subset of the parameters changed. Specifically, I would like to be able to change the values of a subset of parameters by named reference rather than by index. I found the following syntax in the SciML docs (Optimizing through an ODE solve and re-creating MTK Problems · ModelingToolkit.jl) (full code below).

@Bill_Holmes

This is however really clunky and more prone to introducing errors.

This should be a standard issue, and I am pulling the syntax directly from the SciML docs. The docs are really well done so I’m assuming I have either a typo or a mis-understanding of how the structures are handled in the background.

Any thoughts on where I am going wrong or suggestions for a better way to do this?

I’m not sure what else to say other than these are almost precisely the breaking changes that led to ModelingToolkit v9. The reason for the initialization system, missing values for parameter equations, and the new SymbolicIndexingInterface.jl were made to solve this issue. There won’t be a backporting of that to MTK v8 because the breaking changes that were made were to facilitate making these features and thus required for solving these problems. I wish I had an easier answer but I don’t think it can be robustly done on v8.

But also, what is the issue you are having with the update? That may be the simpler thing to solve.