Fix an error in the demo code for ceres::Jet.
The example code for ceres::Jet is incorrect since it misses at which point
the derivate is computed.
Change-Id: Ic3f2ee061a2b69f0a402ca1a01297ddda1f153cd
diff --git a/include/ceres/jet.h b/include/ceres/jet.h
index 082bcc3..2b54064 100644
--- a/include/ceres/jet.h
+++ b/include/ceres/jet.h
@@ -102,8 +102,9 @@
// }
//
// // The "2" means there should be 2 dual number components.
-// Jet<double, 2> x(0); // Pick the 0th dual number for x.
-// Jet<double, 2> y(1); // Pick the 1st dual number for y.
+// // It computes the partial derivative at x=10, y=20.
+// Jet<double, 2> x(10, 0); // Pick the 0th dual number for x.
+// Jet<double, 2> y(20, 1); // Pick the 1st dual number for y.
// Jet<double, 2> z = f(x, y);
//
// LOG(INFO) << "df/dx = " << z.v[0]
