Compare minima for the trivial function

src/test-gradient-method.cc

@@ -152,7 +152,14 @@ void testTrivialFunction() {
   error -= returned;
   assert(error.two_norm() < 1e-10); // FIXME: 1e-10 sounds reasonable. Is it?
 
-  functionTester(J, start, 5);
+  double const ret1 = functionTester(J, start, 6);
+  std::cout << std::endl;
+
+  start[0] = 279;
+  start[1] = -96;
+
+  double const ret2 = functionTester(J, start, 16);
+  assert(std::abs(ret1 - ret2) < 1e-5);
 }
 
 int main() {