Terminate simulation on event using ModelingToolkit

General Usage
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1

Hi all,

First of all, thank you all for your immense efforts on Julia and ModelingToolkit. I’ve been using it for over 2 years and I keep being impressed with the power and capabilities.

I’m trying to terminate an MTK simulation using an event description.

I have a minimal example below:

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D

function affect!(mod,obs,ctx,int)
    ModelingToolkit.terminate!(int)
end

function FOL(;name)
    @parameters begin
        τ = 3.0 # parameters
    end
    @variables begin
        x(t) = 0.0 # dependent variables
    end
    eq=[
        D(x) ~ (1 - x) / τ
    ]

    events = [x ~ 0.6]=>(affect!,(;))

    return System(eq, t; name=name, continuous_events=events)
end

using OrdinaryDiffEq
@mtkbuild fol = FOL()
prob = ODEProblem(fol, [], (0.0, 10.0))
sol = solve(prob)

using Plots
plot(sol)

I get the following error. The full description did not fit, so I just pasted the summary.

MethodError: no method matching _generated_writeback(::OrdinaryDiffEqCore.ODEIntegrator{}, ::@NamedTuple{}, ::Vector{Float64})

Closest candidates are:
  _generated_writeback(::Any, ::NamedTuple{NS1}, !Matched::NamedTuple{NS2}) where {NS1, NS2}
   @ ModelingToolkit ~/.julia/packages/ModelingToolkit/80wTI/src/systems/imperative_affect.jl:148

I am running Julia v1.10.10 and MTK v10.26.0.

The problem is very trivial so I am surely missing something obvious…

Kind regards,

Koen Linders

2

Open an issue. I’m surprised that didn’t just work but we haven’t tested using terminations yet.

3

Thank you for the response Chris! I’ll make an issue :+1:

4

Actually it was a small easy bug

5

Just for good bookkeeping: The issue was solved by @cryptic.ax on Github.

The solution is returning an empty NamedTuple like so

function affect!(mod,obs,ctx,int)
    ModelingToolkit.terminate!(int)

    return (;)
end

Thank you all for your help