expose tofloat for ODEProblem (#1878)

Author: bradcarman

src/systems/diffeqs/abstractodesystem.jl

@@ -550,6 +550,7 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
                            linenumbers = true, parallel = SerialForm(),
                            eval_expression = true,
                            use_union = false,
+                           tofloat = !use_union,
                            kwargs...)
     eqs = equations(sys)
     dvs = states(sys)
@@ -561,7 +562,7 @@ function process_DEProblem(constructor, sys::AbstractODESystem, u0map, parammap;
     defs = mergedefaults(defs, u0map, dvs)
 
     u0 = varmap_to_vars(u0map, dvs; defaults = defs, tofloat = true)
-    p = varmap_to_vars(parammap, ps; defaults = defs, tofloat = !use_union, use_union)
+    p = varmap_to_vars(parammap, ps; defaults = defs, tofloat, use_union)
     p = p === nothing ? SciMLBase.NullParameters() : p
 
     if implicit_dae && du0map !== nothing