diff --git a/examples/FisheyeExample.cpp b/examples/FisheyeExample.cpp
index 2f79eb667..b03c9a71d 100644
--- a/examples/FisheyeExample.cpp
+++ b/examples/FisheyeExample.cpp
@@ -10,11 +10,12 @@
  * -------------------------------------------------------------------------- */
 
 /**
- * @file    VisualBatchExample.cpp
+ * @file    FisheyeExample.cpp
  * @brief   A visualSLAM example for the structure-from-motion problem on a
  * simulated dataset. This version uses a fisheye camera model and a  GaussNewton
  * solver to solve the graph in one batch
  * @author  ghaggin
+ * @Date    Apr 9,2020
  */
 
 /**
diff --git a/gtsam/geometry/Cal3Fisheye.h b/gtsam/geometry/Cal3Fisheye.h
index df2978350..8fd22cedc 100644
--- a/gtsam/geometry/Cal3Fisheye.h
+++ b/gtsam/geometry/Cal3Fisheye.h
@@ -11,7 +11,7 @@
 
 /**
  * @file Cal3Fisheye.h
- * @brief Calibration of a fisheye, calculations in base class Cal3Fisheye_Base
+ * @brief Calibration of a fisheye camera, calculations in base class Cal3Fisheye_Base
  * @date Apr 8, 2020
  * @author ghaggin
  */
diff --git a/gtsam/geometry/Cal3Fisheye_Base.cpp b/gtsam/geometry/Cal3Fisheye_Base.cpp
index 19f7d010b..4b51276df 100644
--- a/gtsam/geometry/Cal3Fisheye_Base.cpp
+++ b/gtsam/geometry/Cal3Fisheye_Base.cpp
@@ -81,11 +81,12 @@ static Matrix2 D2dintrinsic(const double xi, const double yi, const double r, co
   const double dtd_dxi = dtd_dt * dt_dr * dr_dxi;
   const double dtd_dyi = dtd_dt * dt_dr * dr_dyi;
 
-  const double rr = r*r;
-  const double dxd_dxi = dtd_dxi*xi*(1/r) + td*(1/r) + td*xi*(-1/rr)*dr_dxi;
-  const double dxd_dyi = dtd_dyi*xi*(1/r) + td*xi*(-1/rr)*dr_dyi;
-  const double dyd_dxi = dtd_dxi*yi*(1/r) + td*yi*(-1/rr)*dr_dxi;
-  const double dyd_dyi = dtd_dyi*yi*(1/r) + td*(1/r) + td*yi*(-1/rr)*dr_dyi;
+  const double rinv = 1/r;
+  const double rrinv = 1/(r*r); 
+  const double dxd_dxi = dtd_dxi*xi*rinv + td*rinv + td*xi*(-rrinv)*dr_dxi;
+  const double dxd_dyi = dtd_dyi*xi*rinv - td*xi*rrinv*dr_dyi;
+  const double dyd_dxi = dtd_dxi*yi*rinv - td*yi*rrinv*dr_dxi;
+  const double dyd_dyi = dtd_dyi*yi*rinv + td*rinv + td*yi*(-rrinv)*dr_dyi;
 
   Matrix2 DR;
   DR << dxd_dxi, dxd_dyi, dyd_dxi, dyd_dyi;