The functional series forms a periodic function

Dmytro Boiko

New member
Joined
Jul 28, 2020
Messages
1
I have a functional series of this kind
[MATH]f(x) = \sum_{n=0}^{\infty} \cfrac{1}{\sqrt{s^2 + l^2(2 n + 1 + (-1)^n x)^2}}[/MATH]During the study there is an assumption about the periodicity
[MATH]f(x) = f(x + 4k), \quad k \in \mathbb{Z} [/MATH]The amplitude varies within
[MATH]m_1= \sum_{n=0}^{\infty} \cfrac{1}{\sqrt{s^2 + l^2(2 n + 1 + (-1)^n)^2}}[/MATH][MATH]m_2 = \sum_{n=0}^{\infty} \cfrac{1}{\sqrt{s^2 + l^2(2 n + 1 - (-1)^n)^2}}[/MATH]Безымянный.pngБезымянный.png


Has anyone encountered functions of this kind?
How can you prove the periodicity?
Is it possible to find another species without using a series?

Thank you very much, I'm sorry if not in that topic.
 
Top