@define mkpi(n)
{
	@local k, s, a;
	s = 0;
	a = 1;
	for(k = 0; k < n; k++){
		s += a/(float)(2*k+1);
		a *= -1;
	}
	return 4*s;
}
foreach(@lambda(n){ printf("%f\n", mkpi(n)); },
	[ 1, 10, 100, 1000, 10000 ]);