- #1
Bachelier
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1. Is this the only example of a function ##f(x) \in C^1([0,1])## with discontinuous derivative
$$f(x) = \begin{cases}
x^2 sin(\frac{1}{x}) & \textrm{ if }x ≠ 0 \\
0 & \textrm{ if }x = 0 \\
\end{cases}$$
It seems this example is over-used. Do we have other examples besides this one in whatever metric space?2. Also, can a function from a disjoint set be continuous (under the usual metric)?
For instance
$$f(x) = \begin{cases}
x^2 sin(\frac{1}{x}) & \textrm{ if }x ≠ 0 \\
0 & \textrm{ if }x = 0 \\
\end{cases}$$
It seems this example is over-used. Do we have other examples besides this one in whatever metric space?2. Also, can a function from a disjoint set be continuous (under the usual metric)?
For instance
##H(x) \ : \ [-∞,-1] \cup [1,∞] → \mathbb{R}##
## \hspace{5 cm} x \mapsto |x| ##
## \hspace{5 cm} x \mapsto |x| ##
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