I made the following additions to the code above to convert it to use SDEProblem.

```
forcing!(du,u,p,t) = (du .= 0)
noise!(du,u,p,t) = (du .= 0)
W = WienerProcess(0.0,0.0,0.0)
prob = SDEProblem(forcing!, noise!, u₀, tspan, p, noise = W)
jump_prob = JumpProblem(prob, Direct(), rj)
sol = solve(jump_prob, TauLeaping(), dt = δt, maxiters = 1e5)
sol_array = zeros(5, length(sol))
sol_array[1:4, :] = Array(sol)
sol_array[5, :] = sum(sol_array[1:4, :], dims = 1)
```

This works, but only with `EM()`

solver, and not with `TauLeaping()`

. It seems like only `EM()`

and `ImplicitEM()`

are compatible with RegularJump problems, according to the JumpProccesses.jl documentation.

`TauLeaping()`

produces the following error.

```
julia> sol = solve(jump_prob, TauLeaping(), dt = δt, maxiters = 1e5)
ERROR: The algorithm is not compatible with the chosen noise type. Please see the documentation on the solver methods
Stacktrace:
[1] error(s::String)
@ Base ./error.jl:35
[2] __init(_prob::JumpProblem{true, SDEProblem{Vector{Float64}, Tuple{Float64, Float64}, true, Tuple{Int64, Float64, Float64, Int64}, NoiseProcess{Float64, 1, Float64, Float64, Float64, Vector{Float64}, typeof(DiffEqNoiseProcess.WHITE_NOISE_DIST), typeof(DiffEqNoiseProcess.WHITE_NOISE_BRIDGE), false, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, RSWM{Float64}, Nothing, RandomNumbers.Xorshifts.Xoroshiro128Plus}, SDEFunction{true,SciMLBase.FullSpecialize,…}, typeof(noise!), Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Nothing}, Direct, CallbackSet{Tuple{}, Tuple{}}, Nothing, Tuple{}, RegularJump{true, typeof(rate), typeof(change!), Nothing}, Nothing, TaskLocalRNG, Base.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:callback,), Tuple{Nothing}}}}, alg::TauLeaping, timeseries_init::Vector{Any}, ts_init::Vector{Any}, ks_init::Vector{Any}, recompile::Type{Val{true}}; saveat::Tuple{}, tstops::Tuple{}, d_discontinuities::Tuple{}, save_idxs::Nothing, save_everystep::Bool, save_noise::Bool, save_on::Bool, save_start::Bool, save_end::Nothing, callback::Nothing, dense::Bool, calck::Bool, dt::Float64, adaptive::Bool, gamma::Rational{Int64}, abstol::Nothing, reltol::Nothing, qmin::Rational{Int64}, qmax::Rational{Int64}, qsteady_min::Int64, qsteady_max::Int64, beta2::Nothing, beta1::Nothing, qoldinit::Rational{Int64}, controller::Nothing, fullnormalize::Bool, failfactor::Int64, delta::Rational{Int64}, maxiters::Float64, dtmax::Float64, dtmin::Float64, internalnorm::typeof(DiffEqBase.ODE_DEFAULT_NORM), isoutofdomain::typeof(DiffEqBase.ODE_DEFAULT_ISOUTOFDOMAIN), unstable_check::typeof(DiffEqBase.ODE_DEFAULT_UNSTABLE_CHECK), verbose::Bool, force_dtmin::Bool, timeseries_errors::Bool, dense_errors::Bool, advance_to_tstop::Bool, stop_at_next_tstop::Bool, initialize_save::Bool, progress::Bool, progress_steps::Int64, progress_name::String, progress_message::typeof(DiffEqBase.ODE_DEFAULT_PROG_MESSAGE), userdata::Nothing, initialize_integrator::Bool, seed::UInt64, alias_u0::Bool, alias_jumps::Bool, kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
@ StochasticDiffEq ~/.julia/packages/StochasticDiffEq/0PuS7/src/solve.jl:110
[3] init_call(::JumpProblem{true, SDEProblem{Vector{Float64}, Tuple{Float64, Float64}, true, Tuple{Int64, Float64, Float64, Int64}, NoiseProcess{Float64, 1, Float64, Float64, Float64, Vector{Float64}, typeof(DiffEqNoiseProcess.WHITE_NOISE_DIST), typeof(DiffEqNoiseProcess.WHITE_NOISE_BRIDGE), false, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, RSWM{Float64}, Nothing, RandomNumbers.Xorshifts.Xoroshiro128Plus}, SDEFunction{true,SciMLBase.FullSpecialize,…}, typeof(noise!), Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Nothing}, Direct, CallbackSet{Tuple{}, Tuple{}}, Nothing, Tuple{}, RegularJump{true, typeof(rate), typeof(change!), Nothing}, Nothing, TaskLocalRNG, Base.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:callback,), Tuple{Nothing}}}}, ::TauLeaping, ::Vararg{Any}; merge_callbacks::Bool, kwargshandle::KeywordArgError, kwargs::Base.Pairs{Symbol, Float64, Tuple{Symbol, Symbol}, NamedTuple{(:dt, :maxiters), Tuple{Float64, Float64}}})
@ DiffEqBase ~/.julia/packages/DiffEqBase/JH4gt/src/solve.jl:425
[4] init(::JumpProblem{true, SDEProblem{Vector{Float64}, Tuple{Float64, Float64}, true, Tuple{Int64, Float64, Float64, Int64}, NoiseProcess{Float64, 1, Float64, Float64, Float64, Vector{Float64}, typeof(DiffEqNoiseProcess.WHITE_NOISE_DIST), typeof(DiffEqNoiseProcess.WHITE_NOISE_BRIDGE), false, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, RSWM{Float64}, Nothing, RandomNumbers.Xorshifts.Xoroshiro128Plus}, SDEFunction{true,SciMLBase.FullSpecialize,…}, typeof(noise!), Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Nothing}, Direct, CallbackSet{Tuple{}, Tuple{}}, Nothing, Tuple{}, RegularJump{true, typeof(rate), typeof(change!), Nothing}, Nothing, TaskLocalRNG, Base.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:callback,), Tuple{Nothing}}}}, ::TauLeaping, ::Vararg{Any}; kwargs::Base.Pairs{Symbol, Float64, Tuple{Symbol, Symbol}, NamedTuple{(:dt, :maxiters), Tuple{Float64, Float64}}})
@ DiffEqBase ~/.julia/packages/DiffEqBase/JH4gt/src/solve.jl:442
[5] __solve(jump_prob::JumpProblem{true, SDEProblem{Vector{Float64}, Tuple{Float64, Float64}, true, Tuple{Int64, Float64, Float64, Int64}, NoiseProcess{Float64, 1, Float64, Float64, Float64, Vector{Float64}, typeof(DiffEqNoiseProcess.WHITE_NOISE_DIST), typeof(DiffEqNoiseProcess.WHITE_NOISE_BRIDGE), false, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, RSWM{Float64}, Nothing, RandomNumbers.Xorshifts.Xoroshiro128Plus}, SDEFunction{true,SciMLBase.FullSpecialize,…}, typeof(noise!), Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Nothing}, Direct, CallbackSet{Tuple{}, Tuple{}}, Nothing, Tuple{}, RegularJump{true, typeof(rate), typeof(change!), Nothing}, Nothing, TaskLocalRNG, Base.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:callback,), Tuple{Nothing}}}}, alg::TauLeaping, timeseries::Vector{Any}, ts::Vector{Any}, ks::Vector{Any}, recompile::Type{Val{true}}; kwargs::Base.Pairs{Symbol, Float64, Tuple{Symbol, Symbol}, NamedTuple{(:dt, :maxiters), Tuple{Float64, Float64}}})
@ JumpProcesses ~/.julia/packages/JumpProcesses/8AMkl/src/solve.jl:5
[6] solve(prob::JumpProblem{true, SDEProblem{Vector{Float64}, Tuple{Float64, Float64}, true, Tuple{Int64, Float64, Float64, Int64}, NoiseProcess{Float64, 1, Float64, Float64, Float64, Vector{Float64}, typeof(DiffEqNoiseProcess.WHITE_NOISE_DIST), typeof(DiffEqNoiseProcess.WHITE_NOISE_BRIDGE), false, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, ResettableStacks.ResettableStack{Tuple{Float64, Float64, Float64}, false}, RSWM{Float64}, Nothing, RandomNumbers.Xorshifts.Xoroshiro128Plus}, SDEFunction{true,SciMLBase.FullSpecialize,…}, typeof(noise!), Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, Nothing}, Direct, CallbackSet{Tuple{}, Tuple{}}, Nothing, Tuple{}, RegularJump{true, typeof(rate), typeof(change!), Nothing}, Nothing, TaskLocalRNG, Base.Pairs{Symbol, Nothing, Tuple{Symbol}, NamedTuple{(:callback,), Tuple{Nothing}}}}, args::TauLeaping; kwargs::Base.Pairs{Symbol, Float64, Tuple{Symbol, Symbol}, NamedTuple{(:dt, :maxiters), Tuple{Float64, Float64}}})
@ DiffEqBase ~/.julia/packages/DiffEqBase/JH4gt/src/solve.jl:965
[7] top-level scope
@ code:1
```