How to use sol.retcode to catch ODE instability?

Specific Domains Modelling & Simulations
1

I would like to make an interactive plot with GLMakie. There are some instances when the ODEs generate instability. I would like to plot a label “INSTABILITY DETECTED” in the plot itself when instability occurs.
I understand this can be achieved with sol.retcode but what would be the implementation?
I should set an observable for retcode, then some text that can be written and deleted on the plot when needed.
I could not find an example of an instable ODE and the instability comes out only some times, so it is difficult to provide a working example.
Thank you

2

You would just check SciMLBase.successful_retcode(sol) or sol.retcode and throw a message based on the returned enum

3

Thank you, I wrote something along this line:

data = lift(p_mod) do p_new
    prob = ODEProblem(odeSolver!, u0, tspan, parms)
    return solve(prob, Rosenbrock23(), p = p_new, saveat = R)
    test_instability = sol.retcode
    if test_instability 
        text!(fig, position =  Point2f( 20, 0), "Instability detected", fontsize = 30)
    end
end

Would that be enough? The code works without error but I am unsure if I am hitting an instability given that I got

Warning: At t=0.0, dt was forced below floating point epsilon 5.0e-324, and step error estimate = NaN. Aborting. There is either an error in your model specification or the true solution is unstable (or the true solution can not be represented in the precision of Float64).

on REPL

4

No, if sol.retcode doesn’t mean anything because the return is not a Boolean. Read my previous post