fib.c

#include <stdio.h>
#include <stdlib.h>

double fib(int n)
{
    double a = 1, b = 0, c;
    int i;
    for(i = 1; i <= n; i++) {
        c = b;
        b = a;
        a = a + c;
    }
    return a;
}

int main()
{
    printf("%lf\n", fib(100));
    return 0;
}

fib.kari

(n ->
	1 => a
	0 => b
	for 1 n (
		b => c
		a => b
		+ a c => a
	)
	a
) => fib

fib 100000

fib.py

def fib(n):
	a = 1
	b = 0
	i = 0
	while i < n:
		c = b
		b = a
		a += c
		i += 1
	return a
	
fib(100000)