+// This one called numeric(0).inverse() in heur_gcd().
+static unsigned exam_paranoia13(void)
+{
+ unsigned result = 0;
+ symbol a("a"), b("b"), c("c");
+
+ ex e = c - (b*a-c*a)/(4-a);
+ ex f;
+ ex d = (b*a-4*c)/(a-4);
+ try {
+ f = e.normal();
+ if (!(f - d).expand().is_zero()) {
+ clog << "normal(" << e << ") returns " << f
+ << " instead of " << d << endl;
+ ++result;
+ }
+ } catch (const exception & err) {
+ clog << "normal(" << e << ") cought an exception: "
+ << err.what() << endl;
+ ++result;
+ }
+ return result;
+}
+