Bad error reporting when guess is missing #3185
Description
The following example is missing a guess value for the connector definition HydraulicPortMKR. Because of this when generating the ODEProblem I get a nasty StackOverFlow error. Adding a guess value of 0 for p(t) and m_dot(t) solves the issue. However, I only discovered this after a deep 1hr long dive into the model. It would be good to have the following features:
- better error reproting to identify the problem directly
- a feature that simply provides guess=0 for all variables missing a guess. Maybe a warning is issued if guess values are assumed, but in general it seems silly to put guess=0 next to 90% of the defined variables, and is a very easy thing to forget.
MWE:
using ModelingToolkit
using ModelingToolkit: t_nounits as t
rho0 = 1000
p0 = 0
beta = 1e9
rhof(p) = rho0 * (1 + (p -p0) / beta)
@connector function HydraulicPortMKR(; name)
vars = @variables begin
p(t), []
m_dot(t), [connect = Flow]
end
return ODESystem(Equation[], t, vars, []; name)
end
@component function PressureSource(; name, p::Union{Float64,Int64,Nothing}=nothing)
systems = @named begin
port = HydraulicPortMKR()
end
params = @parameters begin
(p::Float64 = p)
end
eqs = Equation[
port.p ~ p
]
return ODESystem(eqs, t, [], params; systems, name)
end
@component function LaminarOrifice(; name, k::Union{Float64,Int64,Nothing}=nothing)
systems = @named begin
a = HydraulicPortMKR()
b = HydraulicPortMKR()
end
vars = @variables begin
rho(t), [guess = 0.]
end
params = @parameters begin
(k::Float64 = k)
end
eqs = Equation[
rho ~ rhof(a.p)
a.m_dot + b.m_dot ~ 0
a.m_dot ~ k * (a.p - b.p)
]
return ODESystem(eqs, t, vars, params; systems, name)
end
@component function System(; name)
systems = @named begin
pressSource1 = PressureSource(p=105325)
pressSource2 = PressureSource(p=101325)
res1 = LaminarOrifice(k=0.001)
res2 = LaminarOrifice(k=0.001)
end
initialization_eqs = [
# res1.a.m_dot ~ 0
]
eqs = Equation[
connect(pressSource1.port, res1.a)
connect(res1.b, res2.a)
connect(res2.b, pressSource2.port)
]
return ODESystem(eqs, t, [], []; systems, name, initialization_eqs)
end
@mtkbuild model = System()
u0 = []
prob = ODEProblem(model, u0, (0, 5)) # ERROR: StackOverflowErrorThis is using ModelingToolkit v9.49.0
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