What does "user_cache: method has not been implemented for the integrator" mean?

New to Julia
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3

There’s problems with that approach, though. First, when using autodiff, the type constraint on the “user-defined” fields of the data do not match, i.e. only one of the fields is a dual at a time. So, using e.g. Trapezoid() instead of Tsit5 as solver, I get the error:

MethodError: no method matching SimType(::Array{ForwardDiff.Dual{ForwardDiff.Tag{DiffEqBase.UJacobianWrapper{ODEFunction{true,typeof(f),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Float64,DiffEqBase.NullParameters},Float64}(),Float64,2},1}, ::Float64)
Closest candidates are:
  SimType(::Array{T,1}, !Matched::T) where T ...

I remember there is a way of solving this, I read it somewhere some time ago. But, IMO, that’s rather complicated for a “standard user”. Is there any better way?

Ok, so let’s turn off autodiff by using Trapezoid(autodiff=false). I then get:

MethodError: no method matching SimType(::Array{Float64,2}, ::Float64)
Closest candidates are:
  SimType(!Matched::Array{T,1}, ::T) where T ...

So, somehow, this (and many other solvers) try to initialise a 2D array…?