fix: handle array and scalar parameters in split = false systems

Author: AayushSabharwal

src/systems/abstractsystem.jl

@@ -791,8 +791,13 @@ function complete(sys::AbstractSystem; split = true, flatten = true)
             end
             @set! sys.ps = ordered_ps
         end
-    elseif has_index_cache(sys)
-        @set! sys.index_cache = nothing
+    else
+        if has_index_cache(sys)
+            @set! sys.index_cache = nothing
+        end
+        ps = mapreduce(
+            Symbolics.scalarize, vcat, parameters(sys; initial_parameters = true))
+        @set! sys.ps = ps
     end
     if isdefined(sys, :initializesystem) && get_initializesystem(sys) !== nothing
         @set! sys.initializesystem = complete(get_initializesystem(sys); split)

test/split_parameters.jl

@@ -268,3 +268,12 @@ end
         @test_nowarn sol = solve(prob)
     end
 end
+
+@testset "Array and scalar parameters with `split = false`" begin
+    @variables x(t)
+    @parameters p[1:2] q
+    @mtkbuild sys=ODESystem(D(x) ~ sum(p) * x + q, t) split=false
+    @test length(parameters(sys)) == 3
+    prob = ODEProblem(sys, [x => 1.0], (0.0, 1.0), [p => ones(2), q => 1.0])
+    @test prob.p isa Vector{Float64}
+end