Merge pull request #404 from chuongmep/addtripleproduct

Add TripleProduct Method

src/GShark.Test.XUnit/Geometry/Vector3Tests.cs

@@ -236,6 +236,24 @@ public void It_Returns_True_If_Vectors_Are_Equal()
             // Assert
             (vec1 == vec2).Should().BeTrue();
         }
+
+
+        [Theory]
+        [InlineData(new double[] { 1, 2, 3 }, new double[] { 4, 5, 6 }, new double[] { 7, 8, 9 }, 0)]
+        [InlineData(new double[] { 2, 3, -4 }, new double[] { 5, 1, 6 }, new double[] { -7, 8, 9 }, -527)]
+        public void It_Returns_Result_Of_Triple_Product(double[] v1, double[] v2, double[] v3, double expected)
+        {
+            // Arrange
+            Vector3 testVector1 = new Vector3(v1[0], v1[1], v1[2]);
+            Vector3 testVector2 = new Vector3(v2[0], v2[1], v2[2]);
+            Vector3 testVector3 = new Vector3(v3[0], v3[1], v3[2]);
+
+            // Act
+            double result = testVector1.TripleProduct(testVector2, testVector3);
+
+            // Assert
+            result.Should().Be(expected);
+        }
 
         [Fact]
         public void It_Checks_If_Vectors_Are_Perpendicular()

src/GShark/Geometry/Vector3.cs

@@ -706,6 +706,23 @@ public static double DotProduct(Vector3 vector1, Vector3 vector2)
             return result;
         }
 
+
+        /// <summary>
+        /// The triple product of this vector and the two specified vectors.
+        /// </summary>
+        /// <param name="middle">The second vector.</param>
+        /// <param name="right">The third vector.</param>
+        /// <returns>The real number equal to the triple product.</returns>
+        ///<remarks>
+        /// The scalar triple product is defined as the dot product of one of the vectors
+        /// with the cross product of the other two. Geometrically, this product is the (signed)
+        /// volume of the parallelepiped formed by the three vectors given.
+        /// </remarks>
+        public double TripleProduct(Vector3 middle, Vector3 right)
+        {
+           return DotProduct(this, CrossProduct(middle, right));
+        }
+
         ///<summary>
         /// Determines whether this vector is perpendicular to another vector, within a provided angle tolerance. 
         ///</summary>