oneunit(::Type{Any}

[Li-shiyue]

Is it grammatical to construct a system of differential equations in this way? What does this error mean?
function eee!(u, p, t)
x, y = u
a,b,c = p
for i=2:1:99
dx[i] = ax[i-1]+(i+1)x[i+1]-by[i]
dy[i] = (i+1)y[i+1]-iy[i]-cy[i]+bx[i]
end
end
using DifferentialEquations
u1 = []
u2 = []
for i =1:100
push!(u1,0)
push!(u2,0)
end
tspan = (0.0, 20.0)
p = [0.2, 0.04, 20]
u0=[u1,u2]
prob = ODEProblem(eee!, u0, tspan,p)
solve(prob)

ERROR: MethodError: no method matching oneunit(::Type{Any})

Closest candidates are:
oneunit(::Type{Union{Missing, T}}) where T
@ Base missing.jl:105
oneunit(::Type{T}) where T
@ Base number.jl:370
oneunit(::T) where T
@ Base number.jl:369
...

[ChrisRackauckas]

Your issue here is that you don't have a Number element type, you have an array of arrays, which is non-concrete. I recommend turning that array of arrays into a type that has a valid interpretation as a vector, such as as a VectorOfArray from RecursiveArrayTools, or a ComponentArray via ComponentArrays.jl.