mathnet-numerics/src/UnitTests/LinearAlgebraTests/Single/UserDefinedMatrix.cs

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namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Single
{
    using LinearAlgebra.Generic;
    using LinearAlgebra.Single;

    /// <summary>
    /// User-defined matrix implementation (internal class for testing purposes)
    /// </summary>
    internal class UserDefinedMatrix : Matrix
    {
        /// <summary>
        /// Values storage
        /// </summary>
        private readonly float[,] _data;

        /// <summary>
        /// Initializes a new instance of the <see cref="UserDefinedMatrix"/> class. This matrix is square with a given size.
        /// </summary>
        /// <param name="order">the size of the square matrix.</param>
        public UserDefinedMatrix(int order) : base(order, order)
        {
            _data = new float[order, order];
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="UserDefinedMatrix"/> class.
        /// </summary>
        /// <param name="rows">The number of rows.</param>
        /// <param name="columns">The number of columns.</param>
        public UserDefinedMatrix(int rows, int columns) : base(rows, columns)
        {
            _data = new float[rows, columns];
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="UserDefinedMatrix"/> class from a 2D array. 
        /// </summary>
        /// <param name="data">The 2D array to create this matrix from.</param>
        public UserDefinedMatrix(float[,] data) : base(data.GetLength(0), data.GetLength(1))
        {
            _data = (float[,])data.Clone();
        }

        /// <summary>
        /// Retrieves the requested element without range checking.
        /// </summary>
        /// <param name="row">The row of the element.</param>
        /// <param name="column">The column of the element.</param>
        /// <returns>The requested element. </returns>
        public override float At(int row, int column)
        {
            return _data[row, column];
        }

        /// <summary>
        /// Sets the value of the given element.
        /// </summary>
        /// <param name="row">The row of the element.</param>
        /// <param name="column">The column of the element.</param>
        /// <param name="value">The value to set the element to. </param>
        public override void At(int row, int column, float value)
        {
            _data[row, column] = value;
        }

        /// <summary>
        /// Creates a matrix for the given number of rows and columns.
        /// </summary>
        /// <param name="numberOfRows">The number of rows.</param>
        /// <param name="numberOfColumns">The number of columns.</param>
        /// <returns>A matrix with the given dimensions.</returns>
        public override Matrix<float> CreateMatrix(int numberOfRows, int numberOfColumns)
        {
            return new UserDefinedMatrix(numberOfRows, numberOfColumns);
        }

        /// <summary>
        /// Creates a vector with a the given dimension.
        /// </summary>
        /// <param name="size">The size of the vector.</param>
        /// <returns>A vector with the given dimension.</returns>
        public override Vector<float> CreateVector(int size)
        {
            return new UserDefinedVector(size);
        }

        /// <summary>
        /// Initializes a square matrix with all zero's except for ones on the diagonal.
        /// </summary>
        /// <param name="order">the size of the square matrix.</param>
        /// <returns>A identity matrix.</returns>
        public static UserDefinedMatrix Identity(int order)
        {
            var m = new UserDefinedMatrix(order, order);
            for (var i = 0; i < order; i++)
            {
                m[i, i] = 1.0f;
            }

            return m;
        }
    }
}