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using MathNet.Numerics.LinearAlgebra.Double;
using MathNet.Numerics.LinearAlgebra.Storage;

namespace MathNet.Numerics.UnitTests.LinearAlgebraTests.Double
{
    /// <summary>
    /// User-defined matrix implementation (internal class for testing purposes)
    /// </summary>
    internal class UserDefinedMatrix : Matrix
    {
        private class UserDefinedMatrixStorage : MatrixStorage<double>
        {
            public readonly double[,] Data;

            public UserDefinedMatrixStorage(int rowCount, int columnCount)
                : base(rowCount, columnCount)
            {
                Data = new double[rowCount,columnCount];
            }

            public UserDefinedMatrixStorage(int rowCount, int columnCount, double[,] data)
                : base(rowCount, columnCount)
            {
                Data = data;
            }

            public override bool IsDense
            {
                get { return true; }
            }

            public override bool IsFullyMutable
            {
                get { return true; }
            }

            public override bool IsMutableAt(int row, int column)
            {
                return true;
            }

            public override double At(int row, int column)
            {
                return Data[row, column];
            }

            public override void At(int row, int column, double value)
            {
                Data[row, column] = value;
            }
        }

        /// <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(new UserDefinedMatrixStorage(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(new UserDefinedMatrixStorage(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(double[,] data)
            : base(new UserDefinedMatrixStorage(data.GetLength(0), data.GetLength(1), (double[,])data.Clone()))
        {
        }

        /// <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] = 1d;
            }

            return m;
        }
    }
}