Case 02 - Example of a system with custom type to be solved by DifferentialEquations.jl with right solution

test_case_02.jl

importall Base
import RecursiveArrayTools.recursivecopy!

using DifferentialEquations

type SimType{T} <: AbstractArray{T,1}
    x::Array{T,1}

    f1::T
end

function SimType{T}(::Type{T}, length::Int64)
    return SimType{T}(zeros(length), T(0))
end

function SimType{T}(S::SimType{T})
    return SimType(T, length(S.x))
end

function SimType{T}(S::SimType{T}, dims::Dims)
    return SimType(T, prod(dims))
end

similar{T}(A::SimType{T}) = begin
    R = SimType(A)
    R.f1 = A.f1
    R
end

similar{T}(A::SimType{T}, ::Type{T}, dims::Dims) = begin
    R = SimType(A, dims)
    R.f1 = A.f1
    R
end

done(A::SimType, i::Int64) = done(A.x,i)
eachindex(A::SimType)      = eachindex(A.x)
next(A::SimType, i::Int64) = next(A.x,i)
start(A::SimType)          = start(A.x)

length(A::SimType) = length(A.x)
ndims(A::SimType)  = ndims(A.x)
size(A::SimType)   = size(A.x)

recursivecopy!(B::SimType, A::SimType) = begin
    recursivecopy!(B.x, A.x)
    B.f1 = A.f1
end

getindex( A::SimType,    i::Int...) = (A.x[i...])
setindex!(A::SimType, x, i::Int...) = (A.x[i...] = x)

function f(t,u,du)
    du[1] = -0.5*u[1] + u.f1
    du[2] = -0.5*u[2]
end

callback = @ode_callback begin
    if t > 5
        for c in cache
            c.f1 = 1.5
        end
    end
    @ode_savevalues
end

u0 = SimType{Float64}([10;10], 0.0)
prob = ODEProblem(f,u0,(0.0,10.0))
sol = solve(prob,callback = callback, tstops = collect(0:0.5:10))