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