[SymmetricMatrix] Override pointwise operations to special case "other" as SymmetricMatrix

Signed-off-by: Alexander Karatarakis <alex@karatarakis.com>

src/Numerics/LinearAlgebra/Double/SymmetricMatrix.cs

@@ -81,6 +81,39 @@
             return this.Clone();
         }
 
+        /// <summary>
+        /// Adds another matrix to this matrix.
+        /// </summary>
+        /// <param name="other">The matrix to add to this matrix.</param>
+        /// <returns>The result of the addition.</returns>
+        /// <exception cref="ArgumentNullException">If the other matrix is <see langword="null"/>.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">If the two matrices don't have the same dimensions.</exception>
+        public override Matrix<double> Add(Matrix<double> other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (other.RowCount != RowCount || other.ColumnCount != ColumnCount)
+            {
+                throw DimensionsDontMatch<ArgumentOutOfRangeException>(this, other);
+            }
+
+            Matrix<double> result;
+            if (other is SymmetricMatrix)
+            {
+                result = CreateMatrix(RowCount, ColumnCount);
+            }
+            else
+            {
+                result = CreateMatrix(RowCount, ColumnCount, true);
+            }
+             
+            DoAdd(other, result);
+            return result;
+        }
+
         /// <summary>
         /// Adds another matrix to this matrix.
         /// </summary>
@@ -122,6 +155,40 @@
             }
         }
 
+        /// <summary>
+        /// Subtracts another matrix from this matrix.
+        /// </summary>
+        /// <param name="other">The matrix to subtract.</param>
+        /// <returns>The result of the subtraction.</returns>
+        /// <exception cref="ArgumentNullException">If the other matrix is <see langword="null"/>.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">If the two matrices don't have the same dimensions.</exception>
+        public override Matrix<double> Subtract(Matrix<double> other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (other.RowCount != RowCount || other.ColumnCount != ColumnCount)
+            {
+                throw DimensionsDontMatch<ArgumentOutOfRangeException>(this, other);
+            }
+
+            Matrix<double> result;
+            if (other is SymmetricMatrix)
+            {
+                result = CreateMatrix(RowCount, ColumnCount);
+            }
+            else
+            {
+                result = CreateMatrix(RowCount, ColumnCount, true);
+            }
+
+            DoSubtract(other, result);
+            return result;
+        }
+
+
         /// <summary>
         /// Subtracts another matrix from this matrix.
         /// </summary>
@@ -246,6 +313,39 @@
             }
         }
 
+        /// <summary>
+        /// Pointwise multiplies this matrix with another matrix.
+        /// </summary>
+        /// <param name="other">The matrix to pointwise multiply with this one.</param>
+        /// <exception cref="ArgumentNullException">If the other matrix is <see langword="null" />.</exception> 
+        /// <exception cref="ArgumentException">If this matrix and <paramref name="other"/> are not the same size.</exception>
+        /// <returns>A new matrix that is the pointwise multiplication of this matrix and <paramref name="other"/>.</returns>
+        public override Matrix<double> PointwiseMultiply(Matrix<double> other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (ColumnCount != other.ColumnCount || RowCount != other.RowCount)
+            {
+                throw DimensionsDontMatch<ArgumentException>(this, other, "other");
+            }
+
+            Matrix<double> result;
+            if (other is SymmetricMatrix)
+            {
+                result = CreateMatrix(RowCount, ColumnCount);
+            }
+            else
+            {
+                result = CreateMatrix(RowCount, ColumnCount, true);
+            }
+
+            PointwiseMultiply(other, result);
+            return result;
+        }
+
         /// <summary>
         /// Pointwise multiplies this matrix with another matrix and stores the result into the result matrix.
         /// </summary>
@@ -281,6 +381,39 @@
             }
         }
 
+        /// <summary>
+        /// Pointwise divide this matrix by another matrix.
+        /// </summary>
+        /// <param name="other">The matrix to pointwise subtract this one by.</param>
+        /// <exception cref="ArgumentNullException">If the other matrix is <see langword="null" />.</exception> 
+        /// <exception cref="ArgumentException">If this matrix and <paramref name="other"/> are not the same size.</exception>
+        /// <returns>A new matrix that is the pointwise division of this matrix and <paramref name="other"/>.</returns>
+        public override Matrix<double> PointwiseDivide(Matrix<double> other)
+        {
+            if (other == null)
+            {
+                throw new ArgumentNullException("other");
+            }
+
+            if (ColumnCount != other.ColumnCount || RowCount != other.RowCount)
+            {
+                throw DimensionsDontMatch<ArgumentException>(this, other);
+            }
+
+            Matrix<double> result;
+            if (other is SymmetricMatrix)
+            {
+                result = CreateMatrix(RowCount, ColumnCount);
+            }
+            else
+            {
+                result = CreateMatrix(RowCount, ColumnCount, true);
+            }
+
+            PointwiseDivide(other, result);
+            return result;
+        }
+
         /// <summary>
         /// Pointwise divide this matrix by another matrix and stores the result into the result matrix.
         /// </summary>