vector: fixed CopyTo bug and added IEnumerable test

src/Numerics/LinearAlgebra/Double/DenseVector.cs

@@ -259,14 +259,16 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             {
                 throw new ArgumentException(Resources.ArgumentVectorsSameLength, "target");
             }
+            
+            if (ReferenceEquals(this, target))
+            {
+                return;
+            }
 
             var otherVector = target as DenseVector;
             if (otherVector == null)
             {
-                for (var index = 0; index < Data.Length; index++)
-                {
-                    target[index] = Data[index];
-                }
+                Parallel.For(0, Data.Length, index => target[index] = Data[index]);
             }
             else
             {

src/Numerics/LinearAlgebra/Double/Vector.cs

@@ -775,8 +775,8 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             if (ReferenceEquals(this, destination))
             {
                 var tmpVector = destination.CreateVector(destination.Count);
-                CopyTo(tmpVector, offset, destinationOffset, count);
-                tmpVector.CopyTo(destination);
+                CopyTo(tmpVector);
+                Parallel.For(0, count, index => destination[destinationOffset + index] = this[offset + index]);
             }
             else
             {

src/UnitTests/LinearAlgebraTests/Double/UserDefinedMatrixTests.cs

@@ -1,7 +1,4 @@
-using System.Collections.Generic;
-using MbUnit.Framework;
-
-namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
+namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
 {
     using LinearAlgebra.Double;
 

src/UnitTests/LinearAlgebraTests/Double/UserDefinedVectorTests.cs

@@ -1,9 +1,7 @@
 namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
 {
-    using System;
     using System.Collections.Generic;
-
-    using MathNet.Numerics.LinearAlgebra.Double;
+    using LinearAlgebra.Double;
 
     internal class UserDefinedVector : Vector
     {

src/UnitTests/LinearAlgebraTests/Double/VectorTests.cs

@@ -6,6 +6,8 @@ using MbUnit.Framework;
 
 namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
 {
+    using System.Collections;
+
     public abstract partial class VectorTests
     {
         private readonly double[] _data = {1, 2, 3, 4, 5};
@@ -65,6 +67,20 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
             Assert.AreEqual(0.0, other[4]);
         }
 
+        [Test]
+        [MultipleAsserts]
+        public void CanCopyPartialVectorToSelf()
+        {
+            var vector = CreateVector(_data);
+            vector.CopyTo(vector, 0, 2, 2);
+
+            Assert.AreEqual(1.0, vector[0]);
+            Assert.AreEqual(2.0, vector[1]);
+            Assert.AreEqual(1.0, vector[2]);
+            Assert.AreEqual(2.0, vector[3]);
+            Assert.AreEqual(5.0, vector[4]);
+        }
+
         [Test]
         [MultipleAsserts]
         public void CanCopyVectorToAnother()
@@ -108,6 +124,21 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
             }
         }
 
+        [Test]
+        [MultipleAsserts]
+        public void CanEnumerateOverVectorUsingIEnumerable()
+        {
+            var vector = CreateVector(_data);
+            var index = 0;
+
+            var enumerable = (IEnumerable)vector;
+            foreach (var element in enumerable)
+            {
+                Assert.AreEqual(index + 1, (double)element);
+                index++;
+            }
+        }
+
         [Test]
         [MultipleAsserts]
         public void CanEquateVectors()