using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(1e-900000000d.Equals(1e-7000d));

        Console.WriteLine(Equal(1e-900000000d, 1e-7000d));

    }

    private static bool Equal(double x, double y)

    {

        if (double.IsInfinity(x) || double.IsInfinity(y))

        {

            return x.Equals(y);

        }

​

        //https://stackoverflow.com/questions/2411392/double-epsilon-for-equality-greater-than-less-than-less-than-or-equal-to-gre

        //The System.Double type can represent values accurate to up to 15 digits. So a simple first order estimate if a double value x is equal to some constant is to use an epsilon of constant * 1E-15

​

        double epsilon = Math.Max(Math.Abs(x), Math.Abs(y)) * 1E-15;

        return Math.Abs(x - y) <= epsilon;

    }

}