Hello everyone!
I’m trying to do a discrete system example, using Difference and Differential functions, when I create the ODEProblem without structural_simplify() I get the results I want.
`using ModelingToolkit
using DifferentialEquations
using Plots
@parameters t
@variablesy(t)=0 x(t)=0
dt = 0.1
Δ = Difference(t; dt=dt,update=true)
D = Differential(t)
eqs = [
Δ(x) ~ t
D(y) ~ x
]
@named sys = ODESystem(eqs,t)
prob = ODEProblem(sys, , (0,1), )
sol = solve(prob, adaptive=false, dt=dt)
plot(sol)`
But when I use structural_simplify() It gives me this error:
sys_simp=structural_simplify(sys) ERROR: ExtraVariablesSystemException: The system is unbalanced. There are 3 highest order derivative variables and 2 equations. More variables than equations, here are the potential extra variable(s): y(t) x(t)
I think it deletes the difference equation, is there a solution to avoid this problem? it’s important for me to keep structural_simplify().