View source for Talk:Period of a function

==Minimal period==
The article states "If a real-valued function $f$ of a real argument is periodic on $X$ (and is not identically equal to a constant), then it has a least period $T_0>0$".  And yet the Dirichlet function $D(x)$, presented two sentences earlier, has no such minimum period.  Presumably some extra condition is missing?  [[User:Richard Pinch|Richard Pinch]] ([[User talk:Richard Pinch|talk]]) 23:06, 20 October 2017 (CEST)
:How ridiculous: a statement follows its counterexample... Well, [https://dic.academic.ru/dic.nsf/enc_mathematics/3932/%D0%9F%D0%95%D0%A0%D0%98%D0%9E%D0%94 the Russian version] contains the adjective "continuous" (but "periodic" is missing there). I'll add "continuos" here. [[User:Boris Tsirelson|Boris Tsirelson]] ([[User talk:Boris Tsirelson|talk]]) 09:28, 21 October 2017 (CEST)