Merge pull request #764 from akohlmey/improved-variable-error-reporting

Improved error messages when defining or evaluating variables

src/variable.h

@@ -97,13 +97,13 @@ class Variable : protected Pointers {
   void remove(int);
   void grow();
   void copy(int, char **, char **);
-  double evaluate(char *, Tree **);
+  double evaluate(char *, Tree **, int ivar=-1);
   double collapse_tree(Tree *);
   double eval_tree(Tree *, int);
   int size_tree_vector(Tree *);
   int compare_tree_vector(int, int);
   void free_tree(Tree *);
-  int find_matching_paren(char *, int, char *&);
+  int find_matching_paren(char *, int, char *&, int ivar=-1);
   int math_function(char *, char *, Tree **, Tree **, int &, double *, int &);
   int group_function(char *, char *, Tree **, Tree **, int &, double *, int &);
   int region_function(char *);
@@ -117,6 +117,7 @@ class Variable : protected Pointers {
   double constant(char *);
   int parse_args(char *, char **);
   char *find_next_comma(char *);
+  void print_var_error(const char *, int, const char *, int);
   void print_tree(Tree *, int);
 };