method to simply plug a cosimulation function into ModelingToolkit.jl ?

[gaelforget]

Is your feature request related to a problem? Please describe.

I have cosimulations that are based on e.g. a fortran based ocean model operated via the ClimateModels.jl interface.

My understanding is that it's possible to plug it in modeling toolkit without implementing FMI, by wrapping my cosimulation in a Julia function of the form f(input , ouput , dt) (?), but this is not well documented.

Describe the solution you’d like

Could documentation for this approach be added?

Describe alternatives you’ve considered

Implementing FMUs for ClimateModels.jl but this will require more effort.

Additional context

Discussed this with @ChrisRackauckas at JuliaEO25.

[ChrisRackauckas]

@AayushSabharwal is this now just handled by array symbolic registration + discrete systems? We should document it.

[AayushSabharwal]

Yep, I think that should work.

[ChrisRackauckas]

Can you document it via an example? Basically just create some ODE directly via DifferentialEquations.jl, and then setup a discrete system to cosimulate that ODE using the discrete system with some MTK model.

@BenChung wanted a similar example, and many other people in chats, so I think it's a good example to have around. Wit hthat I'd call this solved.