Merge pull request #3148 from AayushSabharwal/as/dde-u0-ctor

fix: fix `u0_constructor` for `DDEProblem`/`SDDEProblem`

Author: ChrisRackauckas

src/systems/diffeqs/abstractodesystem.jl

@@ -879,6 +879,7 @@ function DiffEqBase.DDEProblem{iip}(sys::AbstractODESystem, u0map = [],
         check_length = true,
         eval_expression = false,
         eval_module = @__MODULE__,
+        u0_constructor = identity,
         kwargs...) where {iip}
     if !iscomplete(sys)
         error("A completed system is required. Call `complete` or `structural_simplify` on the system before creating a `DDEProblem`")
@@ -892,6 +893,9 @@ function DiffEqBase.DDEProblem{iip}(sys::AbstractODESystem, u0map = [],
     h(p, t) = h_oop(p, t)
     h(p::MTKParameters, t) = h_oop(p..., t)
     u0 = h(p, tspan[1])
+    if u0 !== nothing
+        u0 = u0_constructor(u0)
+    end
 
     cbs = process_events(sys; callback, eval_expression, eval_module, kwargs...)
     kwargs = filter_kwargs(kwargs)
@@ -914,6 +918,7 @@ function DiffEqBase.SDDEProblem{iip}(sys::AbstractODESystem, u0map = [],
         sparsenoise = nothing,
         eval_expression = false,
         eval_module = @__MODULE__,
+        u0_constructor = identity,
         kwargs...) where {iip}
     if !iscomplete(sys)
         error("A completed system is required. Call `complete` or `structural_simplify` on the system before creating a `SDDEProblem`")
@@ -929,6 +934,9 @@ function DiffEqBase.SDDEProblem{iip}(sys::AbstractODESystem, u0map = [],
     h(p::MTKParameters, t) = h_oop(p..., t)
     h(out, p::MTKParameters, t) = h_iip(out, p..., t)
     u0 = h(p, tspan[1])
+    if u0 !== nothing
+        u0 = u0_constructor(u0)
+    end
 
     cbs = process_events(sys; callback, eval_expression, eval_module, kwargs...)
     kwargs = filter_kwargs(kwargs)

test/dde.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, DelayDiffEq, Test
+using ModelingToolkit, DelayDiffEq, StaticArrays, Test
 using SymbolicIndexingInterface: is_markovian
 using ModelingToolkit: t_nounits as t, D_nounits as D
 
@@ -89,6 +89,10 @@ eqs = [D(x(t)) ~ a * x(t) + b * x(t - τ) + c + (α * x(t) + γ) * η]
 prob_mtk = SDDEProblem(sys, [x(t) => 1.0 + t], tspan; constant_lags = (τ,));
 @test_nowarn sol_mtk = solve(prob_mtk, RKMil())
 
+prob_sa = SDDEProblem(
+    sys, [x(t) => 1.0 + t], tspan; constant_lags = (τ,), u0_constructor = SVector{1})
+@test prob_sa.u0 isa SVector{4, Float64}
+
 @parameters x(..) a
 
 function oscillator(; name, k = 1.0, τ = 0.01)
@@ -126,6 +130,10 @@ obsfn = ModelingToolkit.build_explicit_observed_function(
 @test_nowarn sol[[sys.osc1.delx, sys.osc2.delx]]
 @test sol[sys.osc1.delx] ≈ sol(sol.t .- 0.01; idxs = sys.osc1.x).u
 
+prob_sa = DDEProblem(sys, [], (0.0, 10.0); constant_lags = [sys.osc1.τ, sys.osc2.τ],
+    u0_constructor = SVector{4})
+@test prob_sa.u0 isa SVector{4, Float64}
+
 @testset "DDE observed with array variables" begin
     @component function valve(; name)
         @parameters begin