diff --git a/src/Numerics/LinearAlgebra/Double/Matrix.Arithmetic.cs b/src/Numerics/LinearAlgebra/Double/Matrix.Arithmetic.cs
index 745894f5..e3b7d47b 100644
--- a/src/Numerics/LinearAlgebra/Double/Matrix.Arithmetic.cs
+++ b/src/Numerics/LinearAlgebra/Double/Matrix.Arithmetic.cs
@@ -602,5 +602,242 @@ namespace MathNet.Numerics.LinearAlgebra.Double
 
             return rightSide.LeftMultiply(leftSide);
         }
+
+        /// <summary>
+        ///  Concatenates this matrix with the given matrix.
+        /// </summary>
+        /// <param name="right">The matrix to concatenate.</param>
+        /// <returns>The combined matrix.</returns>
+        public virtual Matrix Append(Matrix right)
+        {
+            if (right == null)
+            {
+                throw new ArgumentNullException("right");
+            }
+
+            if (right.RowCount != RowCount)
+            {
+                throw new ArgumentException(Resources.ArgumentMatrixSameRowDimension);
+            }
+
+            Matrix result = CreateMatrix(RowCount, ColumnCount + right.ColumnCount);
+            Append(right, result);
+            return result;
+        }
+
+        /// <summary>
+        /// Concatenates this matrix with the given matrix and places the result into the result matrix.
+        /// </summary>
+        /// <param name="right">The matrix to concatenate.</param>
+        /// <param name="result">The combined matrix.</param>
+        public virtual void Append(Matrix right, Matrix result)
+        {
+            if (right == null)
+            {
+                throw new ArgumentNullException("right");
+            }
+
+            if (right.RowCount != RowCount)
+            {
+                throw new ArgumentException(Resources.ArgumentMatrixSameRowDimension);
+            }
+
+            if (result == null)
+            {
+                throw new ArgumentNullException("result");
+            }
+
+            if (result.ColumnCount != (ColumnCount + right.ColumnCount) || result.RowCount != RowCount)
+            {
+                throw new ArgumentException(Resources.ArgumentMatrixSameColumnDimension);
+            }
+
+            CommonParallel.For(
+               0,
+               this.RowCount,
+               i =>
+               {
+                   for (int j = 0; j < this.ColumnCount; j++)
+                   {
+                       result.At(i, j, At(i, j));
+                   }
+               });
+
+            CommonParallel.For(
+               0,
+               right.RowCount,
+               i =>
+               {
+                   for (int j = 0; j < right.ColumnCount; j++)
+                   {
+                       result.At(i, j + ColumnCount, right.At(i, j));
+                   }
+               });
+        }
+
+        /// <summary>
+        /// Stacks this matrix on top of the given matrix and places the result into the result matrix.
+        /// </summary>
+        /// <param name="lower">The matrix to stack this matrix upon.</param>
+        /// <returns>The combined matrix.</returns>
+        /// <exception cref="ArgumentNullException">If lower is <see langword="null" />.</exception>
+        /// <exception cref="ArgumentException">If <strong>upper.Columns != lower.Columns</strong>.</exception>
+        public virtual Matrix Stack(Matrix lower)
+        {
+            if (lower == null)
+            {
+                throw new ArgumentNullException("lower");
+            }
+
+            if (lower.ColumnCount != ColumnCount)
+            {
+                throw new ArgumentException("lower", Resources.ArgumentMatrixSameColumnDimension);
+            }
+
+            Matrix result = CreateMatrix(RowCount + lower.RowCount, ColumnCount);
+            Stack(lower, result);
+            return result;
+        }
+
+        /// <summary>
+        /// Stacks this matrix on top of the given matrix and places the result into the result matrix.
+        /// </summary>
+        /// <param name="lower">The matrix to stack this matrix upon.</param>
+        /// <param name="result">The combined matrix.</param>
+        /// <exception cref="ArgumentNullException">If lower is <see langword="null" />.</exception>
+        /// <exception cref="ArgumentException">If <strong>upper.Columns != lower.Columns</strong>.</exception>
+        public virtual void Stack(Matrix lower, Matrix result)
+        {
+            if (lower == null)
+            {
+                throw new ArgumentNullException("lower");
+            }
+            
+            if (lower.ColumnCount != ColumnCount)
+            {
+                throw new ArgumentException("lower", Resources.ArgumentMatrixSameColumnDimension);
+            }
+
+            if (result == null)
+            {
+                throw new ArgumentNullException("result");
+            }
+
+            if (result.RowCount != (RowCount + lower.RowCount) || result.ColumnCount != ColumnCount)
+            {
+                throw new ArgumentException("result", Resources.ArgumentMatrixDimensions);
+            }
+           
+            CommonParallel.For(
+                0,
+                this.RowCount,
+                i =>
+                {
+                    for (int j = 0; j < this.ColumnCount; j++)
+                    {
+                        result.At(i, j, At(i, j));
+                    }
+                });
+            
+            CommonParallel.For(
+                0,
+                lower.RowCount,
+                i =>
+                {
+                    for (int j = 0; j < lower.ColumnCount; j++)
+                    {
+                        result.At(i + RowCount, j, lower.At(i, j));
+                    }
+                });
+        }
+
+        /// <summary>
+        /// Computes the trace of this matrix.
+        /// </summary>
+        /// <returns>The trace of this matrix</returns>
+        /// <exception cref=">ArgumentException">If the matrix is not square</exception>
+        public virtual double Trace()
+        {
+            if (RowCount != ColumnCount)
+            {
+                throw new ArgumentException(Resources.ArgumentMatrixSquare);
+            }
+
+            double t = 0.0;
+            for (int i = 0; i < RowCount; i++)
+            {
+                t += this[i, i];
+            }
+
+            return t;
+        }
+
+        /// <summary>
+        /// Diagonally stacks his matrix on top of the given matrix. The new matrix is a M-by-N matrix, 
+        /// where M = this.Rows + lower.Rows and N = this.Columns + lower.Columns.
+        /// The values of off the off diagonal matrices/blocks are set to zero.
+        /// </summary>
+        /// <param name="lower">The lower, right matrix.</param>
+        /// <exception cref="ArgumentNullException">If lower is <see langword="null" />.</exception>
+        /// <returns>the combined matrix</returns>
+        public virtual Matrix DiagonalStack(Matrix lower)
+        {
+            if (lower == null)
+            {
+                throw new ArgumentNullException("lower");
+            }
+
+            Matrix result = CreateMatrix(RowCount + lower.RowCount, ColumnCount + lower.ColumnCount);
+            DiagonalStack(lower, result);
+            return result;
+        }
+
+        /// <summary>
+        /// Diagonally stacks his matrix on top of the given matrix and places the combined matrix into the result matrix.
+        /// </summary>
+        /// <param name="lower">The lower, right matrix.</param>
+        /// <param name="result">The combined matrix</param>
+        /// <exception cref="ArgumentNullException">If lower is <see langword="null" />.</exception>
+        /// <exception cref="ArgumentNullException">If the result matrix is <see langword="null" />.</exception>
+        /// <exception cref="ArgumentException">If the result matrix's dimensions are not (this.Rows + lower.rows) x (this.Columns + lower.Columns).</exception>
+        public virtual void DiagonalStack(Matrix lower, Matrix result)
+        {
+            if (lower == null)
+            {
+                throw new ArgumentNullException("lower");
+            }
+
+            if (result == null)
+            {
+                throw new ArgumentNullException("result");
+            }
+
+            if (result.RowCount != RowCount + lower.RowCount || result.ColumnCount != ColumnCount + lower.ColumnCount)
+            {
+                throw new ArgumentException("result", Resources.ArgumentMatrixDimensions);
+            }
+
+            CommonParallel.For(
+                0,
+                this.RowCount,
+                i =>
+                {
+                    for (var j = 0; j < this.ColumnCount; j++)
+                    {
+                        result.At(i, j, At(i, j));
+                    }
+                });
+
+            CommonParallel.For(
+                0,
+                lower.RowCount,
+                i =>
+                {
+                    for (var j = 0; j < lower.ColumnCount; j++)
+                    {
+                        result.At(i + RowCount, j + ColumnCount, lower.At(i, j));
+                    }
+                });            
+        }
     }
 }
\ No newline at end of file
diff --git a/src/Numerics/LinearAlgebra/Double/Vector.cs b/src/Numerics/LinearAlgebra/Double/Vector.cs
index 774358ce..07adaa61 100644
--- a/src/Numerics/LinearAlgebra/Double/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Double/Vector.cs
@@ -548,6 +548,66 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             result.Multiply(1.0 / scalar);
         }
 
+        /// <summary>
+        /// Pointwise multiplies this vector with another vector.
+        /// </summary>
+        /// <param name="other">The vector to pointwise multiply with this one.</param>
+        /// <exception cref="ArgumentNullException">If the other vector is <see langword="null" />.</exception> 
+        /// <exception cref="ArgumentException">If this vector and <paramref name="other"/> are not the same size.</exception>
+        /// <returns>A new vector that is the pointwise multiplication of this vector and <paramref name="other"/>.</returns>
+        public virtual Vector PointWiseMultiply(Vector other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (Count != other.Count)
+            {
+                throw new ArgumentException(Resources.ArgumentVectorsSameLength, "other");
+            }
+
+            Vector result = CreateVector(Count);
+            PointWiseMultiply(other, result);
+            return result;
+        }
+
+        /// <summary>
+        /// Pointwise multiplies this vector with another vector and stores the result into the result vector.
+        /// </summary>
+        /// <param name="other">The vector to pointwise multiply with this one.</param>
+        /// <param name="result">The vector to store the result of the pointwise multiplication.</param>
+        /// <exception cref="ArgumentNullException">If the other vector is <see langword="null" />.</exception> 
+        /// <exception cref="ArgumentNullException">If the result vector is <see langword="null" />.</exception> 
+        /// <exception cref="ArgumentException">If this vector and <paramref name="other"/> are not the same size.</exception>
+        /// <exception cref="ArgumentException">If this vector and <paramref name="result"/> are not the same size.</exception>
+        public virtual void PointWiseMultiply(Vector other, Vector result)
+        {
+            if (result == null)
+            {
+                throw new ArgumentNullException("result");
+            }
+
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (Count != other.Count)
+            {
+                throw new ArgumentException(Resources.ArgumentVectorsSameLength, "other");
+            }
+
+            if (Count != result.Count)
+            {
+                throw new ArgumentException(Resources.ArgumentVectorsSameLength, "result");
+            }
+
+            CommonParallel.For(
+              0,
+              this.Count,
+              index => result[index] = this[index] * other[index]);
+        }
         #endregion
 
         #region Arithmetic Operator Overloading
diff --git a/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.Arithmetic.cs b/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.Arithmetic.cs
index fbef83e7..ad5da2b2 100644
--- a/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.Arithmetic.cs
+++ b/src/UnitTests/LinearAlgebraTests/Double/MatrixTests.Arithmetic.cs
@@ -579,5 +579,238 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
             Matrix target = CreateMatrix(matrix.RowCount + 1, matrix.ColumnCount);
             matrix.Negate(target);
         }
+
+        [Test]
+        public void Append()
+        {
+            Matrix left = testMatrices["Singular3x3"];
+            Matrix right = testMatrices["Tall3x2"];
+            Matrix result = left.Append(right);
+            Assert.AreEqual(left.ColumnCount + right.ColumnCount, result.ColumnCount);
+            Assert.AreEqual(left.RowCount, right.RowCount);
+
+            for (int i = 0; i < result.RowCount; i++)
+            {
+                for (int j = 0; j < result.ColumnCount; j++)
+                {
+                    if (j < left.ColumnCount)
+                    {
+                        Assert.AreEqual(left[i, j], result[i, j]);
+                    }
+                    else
+                    {
+                        Assert.AreEqual(right[i, j - left.ColumnCount], result[i, j]);
+                    }
+                }
+            }
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void AppendWithRightParameterNullShouldThrowException()
+        {
+            Matrix left = testMatrices["Square3x3"];
+            Matrix right = null;
+            left.Append(right);
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void AppendWithResultParameterNullShouldThrowException()
+        {
+            Matrix left = testMatrices["Square3x3"];
+            Matrix right = testMatrices["Tall3x2"];
+            Matrix result = null;
+            left.Append(right, result);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void AppendingTwoMatricesWithDifferentRowCountShouldThrowException()
+        {
+            Matrix left = testMatrices["Square3x3"];
+            Matrix right = testMatrices["Wide2x3"];
+            Matrix result = left.Append(right);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void AppendingWithInvalidResultMatrixColumnsShouldThrowException()
+        {
+            Matrix left = testMatrices["Square3x3"];
+            Matrix right = testMatrices["Tall3x2"];
+            Matrix result = CreateMatrix(3, 2);
+            left.Append(right, result);
+        }
+
+        [Test]
+        public void Stack()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix bottom = testMatrices["Wide2x3"];
+            Matrix result = top.Stack(bottom);
+            Assert.AreEqual(top.RowCount + bottom.RowCount, result.RowCount);
+            Assert.AreEqual(top.ColumnCount, result.ColumnCount);
+
+            for (int i = 0; i < result.RowCount; i++)
+            {
+                for (int j = 0; j < result.ColumnCount; j++)
+                {
+                    if (i < top.RowCount)
+                    {
+                        Assert.AreEqual(result[i, j], top[i, j]);
+                    }
+                    else
+                    {
+                        Assert.AreEqual(result[i, j], bottom[i - top.RowCount, j]);
+                    }
+                }
+            }
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void StackWithBottomParameterNullShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix bottom = null;
+            Matrix result = CreateMatrix(top.RowCount + top.RowCount, top.ColumnCount);
+            top.Stack(bottom, result);
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void StackWithResultParameterNullShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix bottom = testMatrices["Square3x3"];
+            Matrix result = null;
+            top.Stack(bottom, result);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void StackTwoMatricesWithDifferentColumnsShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix lower = testMatrices["Tall3x2"];
+            Matrix result = CreateMatrix(top.RowCount + lower.RowCount, top.ColumnCount);
+            top.Stack(lower, result);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void StackingWithInvalidResultMatrixRowsShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix bottom = testMatrices["Wide2x3"];
+            Matrix result = CreateMatrix(1, 3);
+            top.Stack(bottom, result);
+        }
+
+        [Test]
+        public void Trace()
+        {
+            Matrix matrix = testMatrices["Square3x3"];
+            double trace = matrix.Trace();
+            Assert.AreEqual(6.6, trace);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void TraceOfNonSquareMatrixShouldThrowException()
+        {
+            Matrix matrix = testMatrices["Wide2x3"];
+            double trace = matrix.Trace();
+        }
+
+        [Test]
+        public void DiagonalStack()
+        {
+            Matrix top = testMatrices["Tall3x2"];
+            Matrix bottom = testMatrices["Wide2x3"];
+            Matrix result = top.DiagonalStack(bottom);
+            Assert.AreEqual(top.RowCount + bottom.RowCount, result.RowCount);
+            Assert.AreEqual(top.ColumnCount + bottom.ColumnCount, result.ColumnCount);
+
+            for (int i = 0; i < result.RowCount; i++)
+            {
+                for (int j = 0; j < result.ColumnCount; j++)
+                {
+                    if (i < top.RowCount && j < top.ColumnCount)
+                    {
+                        Assert.AreEqual(top[i, j], result[i, j]);
+                    }
+                    else if (i >= top.RowCount && j >= top.ColumnCount)
+                    {
+                        Assert.AreEqual(bottom[i - top.RowCount, j - top.ColumnCount], result[i, j]);
+                    }
+                    else
+                    {
+                        Assert.AreEqual(0, result[i, j]);
+                    }
+                }
+            }
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void DiagonalStackWithLowerNullShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix lower = null;
+            top.DiagonalStack(lower);
+        }
+
+        [Test]
+        public void DiagonalStackWithPassingResult()
+        {
+            Matrix top = testMatrices["Tall3x2"];
+            Matrix bottom = testMatrices["Wide2x3"];
+            Matrix result = CreateMatrix(top.RowCount + bottom.RowCount, top.ColumnCount + bottom.ColumnCount);
+            top.DiagonalStack(bottom, result);
+            Assert.AreEqual(top.RowCount + bottom.RowCount, result.RowCount);
+            Assert.AreEqual(top.ColumnCount + bottom.ColumnCount, result.ColumnCount);
+
+            for (int i = 0; i < result.RowCount; i++)
+            {
+                for (int j = 0; j < result.ColumnCount; j++)
+                {
+                    if (i < top.RowCount && j < top.ColumnCount)
+                    {
+                        Assert.AreEqual(top[i, j], result[i, j]);
+                    }
+                    else if (i >= top.RowCount && j >= top.ColumnCount)
+                    {
+                        Assert.AreEqual(bottom[i - top.RowCount, j - top.ColumnCount], result[i, j]);
+                    }
+                    else
+                    {
+                        Assert.AreEqual(0, result[i, j]);
+                    }
+                }
+            }
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void DiagonalStackWithResultNullShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix lower = testMatrices["Wide2x3"];
+            Matrix result = null;
+            top.DiagonalStack(lower,result);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void DiagonalStackWithInvalidResultMatrixShouldThrowException()
+        {
+            Matrix top = testMatrices["Square3x3"];
+            Matrix lower = testMatrices["Wide2x3"];
+            Matrix result = CreateMatrix(top.RowCount + lower.RowCount + 2, top.ColumnCount + lower.ColumnCount);
+            top.DiagonalStack(lower, result);
+
+        }
     }
 }
\ No newline at end of file
diff --git a/src/UnitTests/LinearAlgebraTests/Double/VectorTests.Arithmetic.cs b/src/UnitTests/LinearAlgebraTests/Double/VectorTests.Arithmetic.cs
index f71a02d3..56dee3ae 100644
--- a/src/UnitTests/LinearAlgebraTests/Double/VectorTests.Arithmetic.cs
+++ b/src/UnitTests/LinearAlgebraTests/Double/VectorTests.Arithmetic.cs
@@ -726,5 +726,61 @@ namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
 
             double d = dataA * dataB;
         }
+
+        [Test]
+        public void PointWiseMultiply()
+        {
+            Vector vector1 = CreateVector(_data);
+            Vector vector2 = vector1.Clone();
+            Vector result = CreateVector(vector1.Count);
+            vector1.PointWiseMultiply(vector2, result);
+            for (int i = 0; i < vector1.Count; i++)
+            {
+                Assert.AreEqual(_data[i] * _data[i], result[i]);
+            }
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void PointWiseMultiplyWithOtherNullShouldThrowException()
+        {
+            Vector vector1 = CreateVector(_data);
+            Vector vector2 = null;
+            Vector result = CreateVector(vector1.Count);
+            vector1.PointWiseMultiply(vector2, result);
+        }
+
+        [Test]
+        [ExpectedArgumentNullException]
+        public void PointWiseMultiplyWithResultNullShouldThrowException()
+        {
+            Vector vector1 = CreateVector(_data);
+            Vector vector2 = vector1.Clone();
+            Vector result = null;
+            vector1.PointWiseMultiply(vector2, result);
+        }
+
+        [Test]
+        [ExpectedArgumentException]
+        public void PointWiseMultiplyWithInvalidResultLengthShouldThrowException()
+        {
+            Vector vector1 = CreateVector(_data);
+            Vector vector2 = vector1.Clone();
+            Vector result = CreateVector(vector1.Count + 1);
+            vector1.PointWiseMultiply(vector2, result);
+        }
+
+        [Test]
+        public void PointWiseMultiplyWithResult()
+        {
+            Vector vector1 = CreateVector(_data);
+            Vector vector2 = vector1.Clone();
+            Vector result = vector1.PointWiseMultiply(vector2);
+            for (int i = 0; i < vector1.Count; i++)
+            {
+                Assert.AreEqual(_data[i] * _data[i], result[i]);
+            }
+        }
+
     }
 }
\ No newline at end of file