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//Copyright � 2009 Jose Antonio De Santiago-Castillo
//E-mail:JAntonioDeSantiago@gmail.com
//Web: www.DotNumerics.com
//
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
//The matrix A is symmetric if it has the property A = AT, which means:
//It has the same number of rows as it has columns; that is, it has n rows and n columns.
//The value of every element aij on one side of the main diagonal equals its mirror
//image aji on the other side: aij = aji for 1 <= i <= n and 1 <= j <= n.
namespace DotNumerics.LinearAlgebra
{
/// <summary>
/// Represents a symmetric matrix.
/// </summary>
public sealed class SymmetricMatrix : BaseMatrix
{
#region Public Constructors
/// <summary>
/// Initializes a new instance of the SymmetricMatrix class of the given size.
/// </summary>
/// <param name="size">Size</param>
public SymmetricMatrix(int size) : base(size) { }
/// <summary>
/// Initializes a new instance of the SymmetricMatrix class of the given size using a array
/// </summary>
/// <param name="size">Size</param>
/// <param name="Data">The data</param>
internal SymmetricMatrix(int size, double[] Data) : base(size, Data) { }
#endregion
#region Public Methods
/// <summary>
/// Returns the value of a element of the matrix.
/// </summary>
/// <param name="row">The row value (zero-based).</param>
/// <param name="column">The column value (zero-based).</param>
/// <returns>The matrix value at (row, column).</returns>
public override double this[int row, int column]
{
get
{
if (column >= this._ColumnCount)
{
throw new ArgumentException("Index was outside the bounds of the matrix.");
}
return this._Data[row + column * this._RowCount];
}
set
{
if (column >= this._ColumnCount)
{
throw new ArgumentException("Index was outside the bounds of the matrix.");
}
//aij = aji for 1 <= i <= n and 1 <= j <= n.
this._Data[row + column * this._RowCount] = value;
this._Data[column + row * this._RowCount] = value;
}
}
public SymmetricMatrix Clone()
{
SymmetricMatrix NewMatrix = new SymmetricMatrix(this._RowCount, this._Data);
return NewMatrix;
}
#region Static methods
#region Static methods
/// <summary>
/// Generate a matrix with random elements
/// </summary>
/// <param name="size">Size</param>
/// <returns>An m-by-n matrix with uniformly distributed
/// random elements in <c>[0, 1)</c> interval.</returns>
public static SymmetricMatrix Random(int size)
{
System.Random random = new System.Random();
SymmetricMatrix X = new SymmetricMatrix(size);
double[] XData = X.Data;
for (int j = 0; j < X.ColumnCount; j++)
{
for (int i = 0; i < X.RowCount; i++)
{
X[i, j] = random.NextDouble();
}
}
return X;
}
/// <summary>
/// Generate a matrix with random elements
/// </summary>
/// <param name="size">Size</param>
/// <param name="Seed">
/// A number used to calculate a starting value for the pseudo-random number
/// sequence. If a negative number is specified, the absolute value of the number
/// is used.
/// </param>
/// <returns>An m-by-n matrix with uniformly distributed
/// random elements in <c>[0, 1)</c> interval.</returns>
public static SymmetricMatrix Random(int size, int Seed)
{
System.Random random = new System.Random(Seed);
SymmetricMatrix X = new SymmetricMatrix(size);
double[] XData = X.Data;
for (int j = 0; j < X.ColumnCount; j++)
{
for (int i = 0; i < X.RowCount; i++)
{
X[i, j] = random.NextDouble();
}
}
return X;
}
#endregion
#endregion
#endregion
#region Overloading Operators
/// <summary>
/// Matrix addition.
/// </summary>
/// <param name="A">The left side matrix of the addition operator.</param>
/// <param name="B">The right side matrix of the addition operator.</param>
/// <returns>A matrix that represents the result of the matrix addition.</returns>
public static SymmetricMatrix operator +(SymmetricMatrix A, SymmetricMatrix B)
{
if (B.RowCount != A.RowCount || B.ColumnCount != A.ColumnCount)
{
throw new System.ArgumentException("Matrix dimensions are not valid.");
}
SymmetricMatrix C = new SymmetricMatrix(A.RowCount);
double[] AData = A.Data;
double[] BData = B.Data;
double[] CData = C.Data;
for (int i = 0; i < AData.Length; i++)
{
CData[i] = AData[i] + BData[i];
}
return C;
}
/// <summary>
/// Matrix subtraction.
/// </summary>
/// <param name="A"> The left side matrix of the subtraction operator.</param>
/// <param name="B">The right side matrix of the subtraction operator.</param>
/// <returns>A matrix that represents the result of the matrix subtraction.</returns>
public static SymmetricMatrix operator -(SymmetricMatrix A, SymmetricMatrix B)
{
if (B.RowCount != A.RowCount || B.ColumnCount != A.ColumnCount)
{
throw new System.ArgumentException("Matrix dimensions are not valid.");
}
SymmetricMatrix C = new SymmetricMatrix(A.RowCount);
double[] AData = A.Data;
double[] BData = B.Data;
double[] CData = C.Data;
for (int i = 0; i < AData.Length; i++)
{
CData[i] = AData[i] - BData[i];
}
return C;
}
#region Scalar-Matrix Multiplication
/// <summary>
/// Scalar-Matrix multiplication.
/// </summary>
/// <param name="s"> The left side scalar of the multiplication operator.</param>
/// <param name="A">The right side matrix of the multiplication operator.</param>
/// <returns>A matrix that represents the result of the multiplication.</returns>
public static SymmetricMatrix operator *(double s, SymmetricMatrix A)
{
SymmetricMatrix C = new SymmetricMatrix(A.RowCount);
double[] AData = A.Data;
double[] CData = C.Data;
Matrix.MultiplicationSM(s, AData, CData);
return C;
}
/// <summary>
/// Implicit SymmetricMatrix to Matrix conversion.
/// </summary>
/// <param name="symmetricMatrix">The SymmetricMatrix.</param>
/// <returns>The matrix.</returns>
public static implicit operator Matrix(SymmetricMatrix symmetricMatrix)
{
Matrix NewMatrix = new Matrix(symmetricMatrix.RowCount, symmetricMatrix.ColumnCount, symmetricMatrix.Data);
return NewMatrix;
}
#endregion
#endregion
}
}
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