refactor: only display singular warning if warn_initialize_determined

Author: AayushSabharwal

src/structural_transformation/utils.jl

@@ -123,16 +123,15 @@ function check_consistency(state::TransformationState, orig_inputs; nothrow = fa
     unassigned_var = singular_check(state)
 
     if !isempty(unassigned_var) || !is_balanced
+        if nothrow
+            return false
+        end
         io = IOBuffer()
         Base.print_array(io, unassigned_var)
         unassigned_var_str = String(take!(io))
         errmsg = "The system is structurally singular! " *
                  "Here are the problematic variables: \n" *
                  unassigned_var_str
-        if nothrow
-            @warn errmsg
-            return false
-        end
         throw(InvalidSystemException(errmsg))
     end
 

src/systems/diffeqs/abstractodesystem.jl

@@ -1313,8 +1313,17 @@ function InitializationProblem{iip, specialize}(sys::AbstractODESystem,
                 sys; u0map, initialization_eqs, check_units, pmap = parammap); fully_determined)
     end
 
-    if !isempty(StructuralTransformations.singular_check(get_tearing_state(isys)))
-        @warn "Since the initialization system is singular, the guess values may significantly affect the initial values of the ODE"
+    ts = get_tearing_state(isys)
+    if warn_initialize_determined &&
+       (unassigned_vars = StructuralTransformations.singular_check(ts); !isempty(unassigned_vars))
+        errmsg = """
+        The initialization system is structurally singular. Guess values may \
+        significantly affect the initial values of the ODE. The problematic variables \
+        are $unassigned_vars.
+
+        Note that the identification of problematic variables is a best-effort heuristic.
+        """
+        @warn errmsg
     end
 
     uninit = setdiff(unknowns(sys), [unknowns(isys); getfield.(observed(isys), :lhs)])

test/initializationsystem.jl

@@ -955,6 +955,6 @@ end
            D(D(y)) ~ λ * y - g
            x^2 + y^2 ~ 1]
     @mtkbuild pend = ODESystem(eqs, t)
-    @test_warn ["structurally singular", "initialization", "guess"] ODEProblem(
+    @test_warn ["structurally singular", "initialization", "Guess", "heuristic"] ODEProblem(
         pend, [x => 1, y => 0], (0.0, 1.5), [g => 1], guesses = [λ => 1])
 end