Initialization warning when creating certain SDEProblems from Catalyst (but not corresponding ODEProblems

[TorkelE]

Not sure why, but in this context, SDEProblems gives a warning, but not ODEProblems. Also, not too long ago neither of these cases generated warnings. Not sure what is going on.

using Catalyst

# Prepare model.
rn = @reaction_network begin
    (k1,k2), X1 <--> X2
end
u0 = [:X1 => 1.0, :X2 => 2.0]
tspan = (0.0, 1.0)
ps = [:k1 => 3.0, :k2 => 4.0]

ODEProblem(rn, u0, tspan, ps; remove_conserved = true, remove_conserved_warn = false) # No warning.
SDEProblem(rn, u0, tspan, ps; remove_conserved = true, remove_conserved_warn = false) # Gives a `Warning: Initialization system is overdetermined.`

Full warning:

┌ Warning: Initialization system is overdetermined. 1 equations for 0 unknowns. Initialization will default to using least squares. `SCCNonlinearProblem` can only be used for initialization of fully determined systems and hence will not be used here. To suppress this warning pass warn_initialize_determined = false. To make this warning into an error, pass fully_determined = true
└ @ ModelingToolkit ~/.julia/packages/ModelingToolkit/iQ7So/src/systems/diffeqs/abstractodesystem.jl:1349

[rveltz]

why do you mention me?

[TorkelE]

Did I? If so it was highly unintentional, sorry! It might be because you commented on an issue in which I later linked to this issue (SciML/Catalyst.jl#1097), which seems a little bit excessive for you to be notified of.

[vyudu]

Seemingly-related:

ssys = convert(SDESystem, rn)
ModelingToolkit.has_tearing_state(ssys) # false
osys = convert(ODESystem, rn)
ModelingToolkit.has_tearing_state(osys) # true

meaning that an InitializationProblem is not actually constructed for the ODESystem here but is constructed for the SDESystem.

[ChrisRackauckas]

Looks like this is the last one for Catalyst v15 @TorkelE ?

[TorkelE]

Potentially #3347 might have some required remake changes. @AayushSabharwal do you know if there is anything left in remake that we might need? Once everything is done and we have a new MTK release I will go through everything, and then we should hopefully be able to do Catalyst v15 asap.

If Aayush thinks we might still be a while from remake working we might be able to do some Catalyst workaround.