Defing ODEsystem in function and initial conditions outside the function in ModelingToolkit.jl

Specific Domains Numerics
6

Hey,

I should have followed up. I figured out a workaround by declaring the same variables in the function and the executing script. Likely not ideal but works fine for now:

using ModelingToolkit, DifferentialEquations

function init_vars()
        @parameters g
        @variables t, x(t), y(t), c_gp(t)

        @parameters r_g C_α C_φ g C_e
        return  t, x, y, c_gp, g
end 

function init_ODE(u)
        t, x, y, c_gp, g = init_vars()

        D = Differential(t)
        particle_equations = [
                c_gp    ~ - x./ g,
                D(x)   ~  c_gp ,
                D(y)   ~  x-  u(t)
                ]
        return particle_equations
end


u(t) = 7 + 2.0 .* sin.(t .* π ./(60*30))

t, x, y, c_gp, g = init_vars()
z0 = [ x => 0.0,  y => 0.0]
params = [ g  => 9 ]

@named particle_system0 = ODESystem( init_ODE(u) )
particle_system1 = structural_simplify(particle_system0)
problem    = ODEProblem(particle_system1, z0, (0.0,  60*60) , params)

sol  = solve(problem, saveat=60*5)

Both functions can then be put in a module and called from another script.