C# - Fibonacci Zahl mittels Matrix berechnen

 static int fibonacci(int n)
        {
            int[,] fib= {{1,1},{1,0}};
            int[,] blu= {{1,0},{0,1}};
            int a, b, c, d;
        
            while(n > 0)
            {
                if(n % 2 != 0)
                {
                    a = blu[0, 0] * fib[0, 0] + blu[0, 1] * fib[1, 0];
                    b = blu[0, 0] * fib[0, 1] + blu[0, 1] * fib[1, 1];
                    c = blu[1, 0] * fib[0, 0] + blu[1, 1] * fib[1, 0];
                    d = blu[1, 0] * fib[0, 1] + blu[1, 1] * fib[1, 1];

                    blu[0, 0] = a;
                    blu[0, 1] = b;
                    blu[1, 0] = c;
                    blu[1, 1] = d;
                }
        
                a = fib[0, 0] * fib[0, 0] + fib[0, 1] * fib[1, 0];
                b = fib[0, 0] * fib[0, 1] + fib[0, 1] * fib[1, 1];
                c = fib[1, 0] * fib[0, 0] + fib[1, 1] * fib[1, 0];
                d = fib[1, 0] * fib[0, 1] + fib[1, 1] * fib[1, 1];

                fib[0, 0] = a;
                fib[0, 1] = b;
                fib[1, 0] = c;
                fib[1, 1] = d;

                n/=2;
            }
            return (blu[0,1]);
        }