Fix hypot(0,0).
diff --git a/Eigen/src/Core/MathFunctions.h b/Eigen/src/Core/MathFunctions.h
index e1b233d..3c240c2 100644
--- a/Eigen/src/Core/MathFunctions.h
+++ b/Eigen/src/Core/MathFunctions.h
@@ -328,6 +328,7 @@
       p = _y;
       qp = _x / p;
     }
+    if(p==RealScalar(0)) return RealScalar(0);
     return p * sqrt(RealScalar(1) + qp*qp);
   }
 };