Clean up and fix edge case return ordering

Author: YingboMa

src/structural_transformation/pantelides.jl

@@ -96,8 +96,8 @@ function pantelides!(state::TransformationState, ag::Union{AliasGraph, Nothing}
                 var′ === nothing && break
                 var = var′
             end
-            if !isempty(𝑑neighbors(graph, var)) || (ag !== nothing && haskey(ag, var))
-                if haskey(ag, var)
+            if !isempty(𝑑neighbors(graph, var))
+                if ag !== nothing && haskey(ag, var)
                     # TODO: remove lower diff vars from whitelist
                     c, a = ag[var]
                     iszero(c) || (varwhitelist[a] = true)
@@ -107,7 +107,6 @@ function pantelides!(state::TransformationState, ag::Union{AliasGraph, Nothing}
             end
         end
     end
-    @show varwhitelist
 
     if nnonemptyeqs > count(varwhitelist)
         throw(InvalidSystemException("System is structurally singular"))

src/structural_transformation/partial_state_selection.jl

@@ -157,12 +157,13 @@ function partial_state_selection_graph!(structure::SystemStructure, var_eq_match
     var_eq_matching
 end
 
-function dummy_derivative_graph!(state::TransformationState, jac = nothing, ag = nothing;
+function dummy_derivative_graph!(state::TransformationState, jac = nothing,
+                                 (ag, diff_va) = (nothing, nothing);
                                  kwargs...)
     state.structure.solvable_graph === nothing && find_solvables!(state; kwargs...)
-    var_eq_matching = complete(pantelides!(state, ag === nothing ? nothing : first(ag)))
+    var_eq_matching = complete(pantelides!(state, ag))
     complete!(state.structure)
-    dummy_derivative_graph!(state.structure, var_eq_matching, jac, ag)
+    dummy_derivative_graph!(state.structure, var_eq_matching, jac, (ag, diff_va))
 end
 
 function compute_diff_level(diff_to_x)
@@ -185,7 +186,6 @@ end
 function dummy_derivative_graph!(structure::SystemStructure, var_eq_matching, jac,
                                  (ag, diff_va))
     @unpack eq_to_diff, var_to_diff, graph = structure
-    display(structure)
     diff_to_eq = invview(eq_to_diff)
     diff_to_var = invview(var_to_diff)
     invgraph = invview(graph)
@@ -197,7 +197,6 @@ function dummy_derivative_graph!(structure::SystemStructure, var_eq_matching, ja
     dummy_derivatives = Int[]
     col_order = Int[]
     nvars = ndsts(graph)
-    @info "" var_eq_matching
     for vars in var_sccs
         eqs = [var_eq_matching[var] for var in vars if var_eq_matching[var] !== unassigned]
         isempty(eqs) && continue
@@ -249,15 +248,17 @@ function dummy_derivative_graph!(structure::SystemStructure, var_eq_matching, ja
             vars = [diff_to_var[var] for var in vars if diff_to_var[var] !== nothing]
         end
     end
-    n_dummys = length(dummy_derivatives)
-    needed = count(x -> x isa Int, diff_to_eq) - n_dummys
-    n = 0
-    for v in diff_va
-        c, a = ag[v]
-        n += 1
-        push!(dummy_derivatives, iszero(c) ? v : a)
-        needed == n && break
-        continue
+    if diff_va !== nothing
+        n_dummys = length(dummy_derivatives)
+        needed = count(x -> x isa Int, diff_to_eq) - n_dummys
+        n = 0
+        for v in diff_va
+            c, a = ag[v]
+            n += 1
+            push!(dummy_derivatives, iszero(c) ? v : a)
+            needed == n && break
+            continue
+        end
     end
 
     dummy_derivatives_set = BitSet(dummy_derivatives)

src/systems/alias_elimination.jl

@@ -8,7 +8,7 @@ function alias_eliminate_graph!(state::TransformationState)
     mm = linear_subsys_adjmat(state)
     if size(mm, 1) == 0
         ag = AliasGraph(ndsts(state.structure.graph))
-        return ag, ag, mm, mm, BitSet() # No linear subsystems
+        return ag, mm, ag, mm, BitSet() # No linear subsystems
     end
 
     @unpack graph, var_to_diff = state.structure