detect input variables after conversion to parameters

Author: baggepinnen

src/inputoutput.jl

@@ -5,7 +5,7 @@ using Symbolics: get_variables
 Return all variables that mare marked as inputs. See also [`unbound_inputs`](@ref)
 See also [`bound_inputs`](@ref), [`unbound_inputs`](@ref)
 """
-inputs(sys) = filter(isinput, states(sys))
+inputs(sys) = [filter(isinput, states(sys)); filter(isinput, parameters(sys))]
 
 """
     outputs(sys)
@@ -18,6 +18,7 @@ function outputs(sys)
     rhss = [eq.rhs for eq in o]
     lhss = [eq.lhs for eq in o]
     unique([filter(isoutput, states(sys))
+            filter(isoutput, parameters(sys))
             filter(x -> x isa Term && isoutput(x), rhss) # observed can return equations with complicated expressions, we are only looking for single Terms
             filter(x -> x isa Term && isoutput(x), lhss)])
 end

test/input_output_handling.jl

@@ -31,6 +31,12 @@ D = Differential(tv)
 @test !is_bound(sys2, sys.u)
 @test !is_bound(sys2, sys2.sys.u)
 
+# simplification turns input variables into parameters
+ssys = structural_simplify(sys)
+@test ModelingToolkit.isparameter(unbound_inputs(ssys)[])
+@test !is_bound(ssys, u)
+@test u ∈ Set(unbound_inputs(ssys))
+
 fsys2 = flatten(sys2)
 @test is_bound(fsys2, sys.x)
 @test !is_bound(fsys2, sys.u)