From c8907ff5e6739c2d64e0982c1de3c335e9c6b63c Mon Sep 17 00:00:00 2001
From: Davis King <davis@dlib.net>
Date: Mon, 8 Dec 2014 19:56:31 -0500
Subject: [PATCH] Added a length_squared() member to vector.

---
 dlib/geometry/vector.h          | 15 +++++++++++++++
 dlib/geometry/vector_abstract.h |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/dlib/geometry/vector.h b/dlib/geometry/vector.h
index 7f2e50c26..74acd293f 100644
--- a/dlib/geometry/vector.h
+++ b/dlib/geometry/vector.h
@@ -345,6 +345,14 @@ namespace dlib
 
         // ---------------------------------------
 
+        double length_squared(
+        ) const 
+        { 
+            return (double)(x()*x() + y()*y() + z()*z()); 
+        }
+
+        // ---------------------------------------
+
         typename vc_rebind<double,3>::type normalize (
         ) const 
         {
@@ -697,6 +705,13 @@ namespace dlib
 
         // ---------------------------------------
 
+        double length_squared(
+        ) const 
+        { 
+            return (double)(x()*x() + y()*y()); 
+        }
+
+        // ---------------------------------------
 
         typename vc_rebind<double,2>::type normalize (
         ) const 
diff --git a/dlib/geometry/vector_abstract.h b/dlib/geometry/vector_abstract.h
index d5c865c95..c4bbc45cb 100644
--- a/dlib/geometry/vector_abstract.h
+++ b/dlib/geometry/vector_abstract.h
@@ -152,6 +152,13 @@ namespace dlib
                 - returns the length of the vector
         !*/
 
+        double length_squared(
+        ) const;
+        /*!
+            ensures
+                - returns length()*length() 
+        !*/
+
         T& x (
         );
         /*!