17/08/20 08:12:02.38 wGScqPfU.net
|f(a * 2^n) / 2^n - f(a * 2^m) / 2^m|
=
(1 / 2^n) * |f(a * 2^n) - 2^(n - m) * f(a * 2^m)|
=
(1 / 2^n) * |f(a * 2^m * 2^(n - m)) - 2^(n - m) * f(a * 2^m)|
=
(1 / 2^n) * |f(a * 2^m) + … + f(a * 2^m) - f(a * 2^m) - … - f(a * 2^m)|
<
(1 / 2^n) * K (for some positive real number K)
→
0