I was puzzling over the German "mit -KGV(n,m) * PI <= t <= KGV(n,m) * PI".

So, in English math the German KGV(n,m) is the Least Common Multiple of m and n.
LCM(n,m) is lcm(n,m) in Javascript. (n and m are integers in this example.)

German ggt(n,m) is the Greatest (Largest) Common Divisor, (Javascript gcd(n,m).

https://de.wikipedia.org/wiki/Kleinstes_gemeinsames_Vielfaches
(Translatable to English.)

(I do not speak German.)

- Brian