<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">Označme $f(x) := |\sin (x)|$, $x \in [- \pi, \pi ]$.
Spočtěte Fourierovu řadu
$$
f(x) \sim 2 / \pi - 4/ \pi \Left( 
\frac {\cos 2x} {1\cdot 3} +
\frac {\cos 4x} {3\cdot 5} + 
\frac {\cos 6x} {5\cdot 7} + \cdots
\Right)
$$
a zjistěte, kde a jak konverguje.
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