func Fib1(N);   \Return Nth Fibonacci number using iteration
int N;
int Fn, F0, F1;
[F0:= 0;  F1:= 1;  Fn:= N;
while N > 1 do
        [Fn:= F0 + F1;
        F0:= F1;
        F1:= Fn;
        N:= N-1;
        ];
return Fn;
];

func Fib2(N);   \Return Nth Fibonacci number using recursion
int N;
return if N < 2 then N else Fib2(N-1) + Fib2(N-2);

int N;
[for N:= 0 to 20 do [IntOut(0, Fib1(N));  ChOut(0, ^ )];
 CrLf(0);
 for N:= 0 to 20 do [IntOut(0, Fib2(N));  ChOut(0, ^ )];
 CrLf(0);
]