refactor: default allow_algebraic to fully_determined

Author: AayushSabharwal

src/systems/diffeqs/abstractodesystem.jl

@@ -1455,6 +1455,7 @@ function InitializationProblem{iip, specialize}(sys::AbstractSystem,
         allow_incomplete = false,
         force_time_independent = false,
         algebraic_only = false,
+        allow_algebraic = nothing,
         kwargs...) where {iip, specialize}
     if !iscomplete(sys)
         error("A completed system is required. Call `complete` or `structural_simplify` on the system before creating an `ODEProblem`")
@@ -1482,7 +1483,7 @@ function InitializationProblem{iip, specialize}(sys::AbstractSystem,
     end
 
     if simplify_system
-        isys = structural_simplify(isys; fully_determined)
+        isys = structural_simplify(isys; fully_determined, allow_algebraic)
     end
 
     meta = get_metadata(isys)

src/systems/systems.jl

@@ -25,19 +25,20 @@ topological sort of the observed equations in `sys`.
 ### Optional Keyword Arguments:
 + When `simplify=true`, the `simplify` function will be applied during the tearing
   process.
-+ `allow_symbolic=false`, `allow_algebraic=true`, `allow_parameter=true`, and
++ `allow_symbolic=false`, `allow_algebraic=nothing`, `allow_parameter=true`, and
   `conservative=false` limit the coefficient types during tearing. In particular,
   `conservative=true` limits tearing to only solve for trivial linear systems where
   the coefficient has the absolute value of ``1``. `allow_symbolic` allows arbitrary
   symbolic coefficients. If it is false, `allow_algebraic` allows symbolic coefficients
   involving only algebraic variables and parameters. Otherwise, `allow_parameter` only
-  allows coefficients containing parameters.
+  allows coefficients containing parameters. `allow_algebraic` defaults to
+  `fully_determined` if `nothing`.
 + `fully_determined=true` controls whether or not an error will be thrown if the number
   of equations don't match the number of inputs, outputs, and equations.
 """
 function structural_simplify(
         sys::AbstractSystem, io = nothing; additional_passes = [], simplify = false, split = true,
-        allow_symbolic = false, allow_algebraic = true, allow_parameter = true, conservative = false,
+        allow_symbolic = false, allow_algebraic = nothing, allow_parameter = true, conservative = false,
         fully_determined = true, kwargs...)
     isscheduled(sys) && throw(RepeatedStructuralSimplificationError())
     newsys′ = __structural_simplify(sys, io; simplify, allow_symbolic, allow_algebraic,

src/systems/systemstructure.jl

@@ -693,7 +693,7 @@ end
 
 function _structural_simplify!(state::TearingState, io; simplify = false,
         check_consistency = true, fully_determined = true, warn_initialize_determined = false,
-        dummy_derivative = true, allow_symbolic = false,
+        dummy_derivative = true, allow_symbolic = false, allow_algebraic = nothing,
         kwargs...)
     if fully_determined isa Bool
         check_consistency &= fully_determined
@@ -710,11 +710,18 @@ function _structural_simplify!(state::TearingState, io; simplify = false,
     else
         input_idxs = 0:-1 # Empty range
     end
-    sys, mm = ModelingToolkit.alias_elimination!(state; allow_symbolic, kwargs...)
+    # use `false` for alias elimination since it doesn't really care about `allow_alebraic`
+    # anyway
+    _allow_algebraic = something(allow_algebraic, false)
+    sys, mm = ModelingToolkit.alias_elimination!(
+        state; allow_symbolic, allow_algebraic = _allow_algebraic, kwargs...)
     if check_consistency
         fully_determined = ModelingToolkit.check_consistency(
             state, orig_inputs; nothrow = fully_determined === nothing)
     end
+    if allow_algebraic === nothing
+        allow_algebraic = fully_determined
+    end
     if fully_determined && dummy_derivative
         sys = ModelingToolkit.dummy_derivative(
             sys, state; simplify, mm, check_consistency, allow_symbolic, kwargs...)