// <copyright file="AssertHelpers.cs" company="Math.NET">
// Math.NET Numerics, part of the Math.NET Project
// http://numerics.mathdotnet.com
// http://github.com/mathnet/mathnet-numerics
//
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using System;
using MathNet.Numerics.LinearAlgebra;

namespace MathNet.Numerics.UnitTests.LinearAlgebraTests
{
    using Complex64 = System.Numerics.Complex;

    /// <summary>
    /// Matrix utility functions to simplify tests.
    /// </summary>
    static public class MatrixHelpers
    {
        /// <summary>
        /// Forces a matrix elements to symmetric. Copies the lower triangle to the upper triangle.
        /// </summary>
        /// <typeparam name="T">The matrix type.</typeparam>
        /// <param name="matrix">The matrix to make symmetric.</param>
        static public void ForceSymmetric<T>(Matrix<T> matrix) where T : struct, IEquatable<T>, IFormattable
        {
            if (matrix.RowCount != matrix.ColumnCount)
            {
                throw new ArgumentException("matrix must be square.", nameof(matrix));
            }
            for (var row = 0; row < matrix.RowCount; row++)
            {
                for (var column = 0; column < row; column++)
                {
                    matrix.At(column, row, matrix.At(row, column));
                }
            }
        }

        /// <summary>
        /// Forces a matrix elements to hermitian (conjugate symmetric). Copies the conjugate of the values
        /// from the lower triangle to the upper triangle.
        /// </summary>
        /// <param name="matrix">The matrix to make conjugate symmetric.</param>
        static public void ForceHermitian(Matrix<Complex64> matrix)
        {
            if (matrix.RowCount != matrix.ColumnCount)
            {
                throw new ArgumentException("matrix must be square.", nameof(matrix));
            }
            for (var row = 0; row < matrix.RowCount; row++)
            {
                for (var column = 0; column < row; column++)
                {
                    matrix.At(column, row, matrix.At(row, column).Conjugate());
                }
            }
        }

        /// <summary>
        /// Forces a matrix elements to conjugate symmetric. Copies the conjugate of the values
        /// from the lower triangle to the upper triangle.
        /// </summary>
        /// <param name="matrix">The matrix to make conjugate symmetric.</param>
        public static void ForceHermitian(Matrix<Numerics.Complex32> matrix)
        {
            if (matrix.RowCount != matrix.ColumnCount)
            {
                throw new ArgumentException("matrix must be square.", nameof(matrix));
            }
            for (var row = 0; row < matrix.RowCount; row++)
            {
                for (var column = 0; column < row; column++)
                {
                    matrix.At(column, row, matrix.At(row, column).Conjugate());
                }
            }
        }
    }
}
