Parallel Fibonacci Number Calculator

Question

I\'m using Task Parallel Library (TPL ) for calculating Fibonacci number. Program is given below:

        public static int Fib(int n)
        {
                     


        

Answer 1

Just for fun :)

using System;
using System.Linq;
using System.Threading.Tasks;

public class Program
{
    static readonly double sqrt5 = Math.Sqrt(5);
    static readonly double p1 = (1 + sqrt5) / 2;
    static readonly double p2 = -1 * (p1 - 1);

    static ulong Fib1(int n) // surprisingly slightly slower than Fib2
    {
        double n1 = Math.Pow(p1, n+1);
        double n2 = Math.Pow(p2, n+1);
        return (ulong)((n1-n2)/sqrt5);
    }

    static ulong Fib2(int n) // 40x faster than Fib3
    {
        double n1 = 1.0;
        double n2 = 1.0;
        for (int i=0; i {
            n1 *= p1; 
            n2 *= p2; 
        });
        return (ulong)((n1-n2)/sqrt5);
    }

    public static void Main(string[] args)
    {
        for (int j=0; j<100000; j++)
            for (int i=0; i<90; i++)
                Fib1(i);
        for (int i=0; i<90; i++)
            Console.WriteLine(Fib1(i));
    }
}