warn if independent variable is repeated

Author: ChrisRackauckas

src/dict_build.jl

@@ -1,11 +1,14 @@
-function build_indvar_dict(ex)
+function build_indvar_dict(ex,depvar)
   indvar_dict = OrderedDict{Symbol,Int}()
   cur_sym = 0
   for i in 2:2:length(ex.args) #Every odd line is line number
     arg = ex.args[i].args[1] #Get the first thing, should be dsomething
     firstarg = Symbol(first(string(arg))) # Check for d
     if firstarg == :d
       nodarg = Symbol(join(Base.Iterators.drop(string(arg), 1)))
+      if nodarg == depvar
+        warn("$depvar is fixed as the independent variable but is also used as a dependent variable. Results my be incorrect.")
+      end
       if !haskey(indvar_dict,nodarg)
         cur_sym += 1
         indvar_dict[nodarg] = cur_sym

src/fem.jl

@@ -2,7 +2,7 @@ macro fem_def(sig,name,ex,params...)
 
   origex = ex
   ## Build Symbol dictionary
-  indvar_dict,syms = build_indvar_dict(ex)
+  indvar_dict,syms = build_indvar_dict(ex,:t)
 
   param_dict, inline_dict = build_paramdicts(params)
   # Run find replace

src/ode_def_opts.jl

@@ -4,7 +4,7 @@ function ode_def_opts(name::Symbol,opts::Dict{Symbol,Bool},ex::Expr,params...;M=
   origex = copy(ex) # Save the original expression
 
   ## Build independent variable dictionary
-  indvar_dict,syms = build_indvar_dict(ex)
+  indvar_dict,syms = build_indvar_dict(ex,depvar)
   ## Build parameter and inline dictionaries
   param_dict, inline_dict = build_paramdicts(params)
   ####