using System;

public class Program

{

    public static void Main()

    {

        var val = 1e-323;

        if(val == 0) throw new Exception("Comparison value got rounded to zero");

        var equal = Equal(0, val);

        Console.WriteLine(equal);

        Console.WriteLine(float.MinValue);

    }

    public static bool Equal(double leftValue, double rightValue, double epsilon = 0.00001)

    {

        // handle infinites (actually equal, both 0.0, etc)

        if (leftValue == rightValue)

        {

            return true;

        }

​

        var diff = Math.Abs(leftValue - rightValue);

​

        if (leftValue == 0f || rightValue == 0f || diff < float.MinValue)

        {

            return diff < epsilon * float.MinValue;

        }

​

        // normalize the difference before comparing it to the epsilon

        var absLeft = Math.Abs(leftValue);

        var absRight = Math.Abs(rightValue);

        return diff / Math.Min(absLeft + absRight, float.MaxValue) < epsilon;

    }

}