Added Vector::sum(), so product() has a friend.

src/Math/Test/VectorTest.cpp

@@ -40,6 +40,7 @@ VectorTest::VectorTest() {
              &VectorTest::length,
              &VectorTest::lengthSquared,
              &VectorTest::normalized,
+             &VectorTest::sum,
              &VectorTest::product,
              &VectorTest::angle,
              &VectorTest::negative,
@@ -121,6 +122,10 @@ void VectorTest::normalized() {
     CORRADE_COMPARE(Vector4(1.0f, 1.0f, 1.0f, 1.0f).normalized(), Vector4(0.5f, 0.5f, 0.5f, 0.5f));
 }
 
+void VectorTest::sum() {
+    CORRADE_COMPARE(Vector3(1.0f, 2.0f, 4.0f).sum(), 7.0f);
+}
+
 void VectorTest::product() {
     CORRADE_COMPARE(Vector3(1.0f, 2.0f, 3.0f).product(), 6.0f);
 }

src/Math/Test/VectorTest.h

@@ -32,6 +32,7 @@ class VectorTest: public Corrade::TestSuite::Tester<VectorTest> {
         void length();
         void lengthSquared();
         void normalized();
+        void sum();
         void product();
         void angle();
         void negative();

src/Math/Vector.h

@@ -268,9 +268,19 @@ template<size_t size, class T> class Vector {
             return *this/length();
         }
 
+        /** @brief Sum of values in the vector */
+        T sum() const {
+            T out(0);
+
+            for(size_t i = 0; i != size; ++i)
+                out += (*this)[i];
+
+            return out;
+        }
+
         /** @brief Product of values in the vector */
         T product() const {
-            T out = 1;
+            T out(1);
 
             for(size_t i = 0; i != size; ++i)
                 out *= (*this)[i];