reduce OrdinaryDiffEq dependency (#216)

Project.toml

@@ -1,12 +1,12 @@
 name = "DynamicalSystemsBase"
 uuid = "6e36e845-645a-534a-86f2-f5d4aa5a06b4"
 repo = "https://github.com/JuliaDynamics/DynamicalSystemsBase.jl.git"
-version = "3.9.1"
+version = "3.10.0"
 
 [deps]
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-OrdinaryDiffEq = "1dea7af3-3e70-54e6-95c3-0bf5283fa5ed"
+OrdinaryDiffEqTsit5 = "b1df2697-797e-41e3-8120-5422d3b24e4a"
 Reexport = "189a3867-3050-52da-a836-e630ba90ab69"
 Roots = "f2b01f46-fcfa-551c-844a-d8ac1e96c665"
 SciMLBase = "0bca4576-84f4-4d90-8ffe-ffa030f20462"
@@ -17,7 +17,7 @@ SymbolicIndexingInterface = "2efcf032-c050-4f8e-a9bb-153293bab1f5"
 
 [compat]
 ForwardDiff = "0.10"
-OrdinaryDiffEq = "6"
+OrdinaryDiffEqTsit5 = "1.1"
 Reexport = "1"
 Roots = "1, 2"
 SciMLBase = "1.19.5, 2"

src/core_systems/continuous_time_ode.jl

@@ -1,4 +1,4 @@
-using OrdinaryDiffEq: Tsit5
+using OrdinaryDiffEqTsit5: Tsit5
 using SciMLBase: ODEProblem, DEIntegrator, u_modified!, __init
 export CoupledODEs, ContinuousDynamicalSystem
 
@@ -46,7 +46,8 @@ When initializing a `CoupledODEs`, you can specify the solver that will integrat
 For example you could use `diffeq = (abstol = 1e-9, reltol = 1e-9)`.
 If you want to specify a solver, do so by using the keyword `alg`, e.g.:
 `diffeq = (alg = Tsit5(), reltol = 1e-6)`. This requires you to have been first
-`using OrdinaryDiffEq` to access the solvers. The default `diffeq` is:
+`using OrdinaryDiffEq` (or smaller library package such as `OrdinaryDiffEqVerner`)
+to access the solvers. The default `diffeq` is:
 
 $(DynamicalSystemsBase.DEFAULT_DIFFEQ)
 
@@ -55,14 +56,13 @@ $(DynamicalSystemsBase.DEFAULT_DIFFEQ)
 
 The convenience constructors `CoupledODEs(prob::ODEProblem [, diffeq])` and
 `CoupledODEs(ds::CoupledODEs [, diffeq])` are also available.
+Use `ODEProblem(ds::CoupledODEs, tspan = (t0, Inf))` to obtain the problem.
+
 To integrate with ModelingToolkit.jl, the dynamical system **must** be created
 via the `ODEProblem` (which itself is created via ModelingToolkit.jl), see
 the Tutorial for an example.
 
 Dev note: `CoupledODEs` is a light wrapper of `ODEIntegrator` from DifferentialEquations.jl.
-The integrator is available as the field `integ`, and the `ODEProblem` is `integ.sol.prob`.
-The convenience syntax `ODEProblem(ds::CoupledODEs, tspan = (t0, Inf))` is available
-to extract the problem.
 """
 struct CoupledODEs{IIP, D, I, P} <: ContinuousTimeDynamicalSystem
     integ::I