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

namespace AtariRobot
{
    public class Math2
    {
        public static double[] Squares(params double[] numbers)
        {
            if (numbers == null)
            {
                throw new ArgumentNullException("The number list cannot be null.");
            }

            int count = numbers.Length;
            double[] squares = new double[count];

            for (int i = 0; i < count; i++)
            {
                double number = numbers[i];
                squares[i] = number * number;
            }

            return squares;
        }

        public static double StandardDeviation(params double[] numbers)
        {
            if (numbers.Length <= 1)
            {
                return -1;
            }

            double average = numbers.Average();

            double[] differences = new double[numbers.Length];
            Array.Copy(numbers, differences, numbers.Length);

            for (int i = 0; i < numbers.Length; i++)
            {
                differences[i] -= average;
            }
            double[] squares = Squares(differences);

            double stdDev = Math.Sqrt((squares.Sum()) / (numbers.Length - 1));
            return stdDev;
        }

        public static double Distance(double x1, double y1, double x2, double y2)
        {
            return Math.Sqrt(((x1 - x2) * (x1 - x2)) + ((y1 - y2) * (y1 - y2)));
        }
    }
}