using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Algorithms.LinearAlgebra.Distances
{
    /// <summary>
    /// Implementation for Euclidean distance.
    /// </summary>
    public static class Euclidean
    {
        /// <summary>
        /// Calculate Euclidean distance for two N-Dimensional points.
        /// </summary>
        /// <param name="point1">First N-Dimensional point.</param>
        /// <param name="point2">Second N-Dimensional point.</param>
        /// <returns>Calculated Euclidean distance.</returns>
        public static double Distance(double[] point1, double[] point2)
        {
            if (point1.Length != point2.Length)
            {
                throw new ArgumentException("Both points should have the same dimensionality");
            }

            // distance = sqrt((x1-y1)^2 + (x2-y2)^2 + ... + (xn-yn)^2)
            return Math.Sqrt(point1.Zip(point2, (x1, x2) => (x1 - x2) * (x1 - x2)).Sum());
        }
    }
}
