Difference between revisions of "Petr function"

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=Properties=
 
=Properties=
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[[The Petr function is continuous]]<br />
<strong>Theorem:</strong> The [[Petr function]] is [[continuous]].
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[[The Petr function is nowhere differentiable]]<br />
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<strong>Proof:</strong> █
 
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<strong>Theorem:</strong> The [[Petr function]] is [[nowhere differentiable]].
 
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<strong>Proof:</strong> █
 
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=References=
 
=References=
 
[https://pure.ltu.se/ws/files/30923977/LTU-EX-03320-SE.pdf]
 
[https://pure.ltu.se/ws/files/30923977/LTU-EX-03320-SE.pdf]
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[[Category:SpecialFunction]]

Latest revision as of 20:34, 25 June 2017

Let $x \in [0,1]$ have decimal representation $x=\displaystyle\sum_{k=1}^{\infty} \dfrac{a_k}{10^k}$, where $a_k \in \{0,1,\ldots,9\}$. The Petr function $P_K \colon [0,1] \rightarrow \mathbb{R}$ is defined by $$P_K(x)=\displaystyle\sum_{k=1}^{\infty} \dfrac{c_k b_k}{2^k},$$ where $b_k = a_k \mod 2, c_1=1$, and for $k \geq 2$, $$c_k = \left\{ \begin{array}{ll} -c_{k-1} &; a_{k-1} \in \{1,3,5,7\}, \\ c_{k-1} &; \mathrm{otherwise}. \end{array} \right.$$

Properties

The Petr function is continuous
The Petr function is nowhere differentiable

References

[1]