WIP: Add initialization_equations flattening constructor

Author: ChrisRackauckas

src/systems/abstractsystem.jl

@@ -879,6 +879,12 @@ function namespace_equation(eq::Equation,
     _lhs ~ _rhs
 end
 
+function namespace_initialization_equations(sys::AbstractSystem, ivs = independent_variables(sys))
+    eqs = initialization_equations(sys)
+    isempty(eqs) && return Equation[]
+    map(eq -> namespace_equation(eq, sys; ivs), eqs)
+end
+
 function namespace_assignment(eq::Assignment, sys)
     _lhs = namespace_expr(eq.lhs, sys)
     _rhs = namespace_expr(eq.rhs, sys)
@@ -1038,6 +1044,20 @@ function equations(sys::AbstractSystem)
     end
 end
 
+function initialization_equations(sys::AbstractSystem)
+    eqs = get_initialization_eqs(sys)
+    systems = get_systems(sys)
+    if isempty(systems)
+        return eqs
+    else
+        eqs = Equation[eqs;
+                       reduce(vcat,
+                           namespace_equations.(get_systems(sys));
+                           init = Equation[])]
+        return eqs
+    end
+end
+
 function preface(sys::AbstractSystem)
     has_preface(sys) || return nothing
     pre = get_preface(sys)

src/systems/diffeqs/abstractodesystem.jl

@@ -907,10 +907,10 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
     # TODO: make it work with clocks
     # ModelingToolkit.get_tearing_state(sys) !== nothing => Requires structural_simplify first
     if sys isa ODESystem && build_initializeprob &&
-       (implicit_dae || !isempty(missingvars)) &&
+       ((implicit_dae || !isempty(missingvars)) &&
        all(isequal(Continuous()), ci.var_domain) &&
-       ModelingToolkit.get_tearing_state(sys) !== nothing &&
-       t !== nothing
+       ModelingToolkit.get_tearing_state(sys) !== nothing) ||
+       !isempty(initialization_equations(sys)) && t !== nothing
         if eltype(u0map) <: Number
             u0map = unknowns(sys) .=> u0map
         end