Difference between revisions of "Takagi function"

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Define $s(x)=\inf_{n \in \mathbb{Z}} |x-n|$ (i.e. the distance from $x$ to the set of integers $\mathbb{Z}$). The Takagi function (also called the blancmange function) is defined by
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The Takagi function (also called the blancmange function) is defined by
$$\mathrm{takagi}(x)=\displaystyle\sum_{k=0}^{\infty} \dfrac{s(2^n x)}{2^n}.$$
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$$\mathrm{takagi}(x)=\displaystyle\sum_{k=0}^{\infty} \dfrac{\mathrm{dist}_{\mathbb{Z}}(2^n x)}{2^n},$$
Note: to calculate $s(x)$ you may use $s(x)=\min \left(2^n x - \lfloor 2^n x \rfloor, \lceil 2^n x \rceil - x \right)$, where $\lfloor \cdot \rfloor$ denotes the [[floor]] function and $\lceil \cdot \rceil$ denotes the [[ceiling]] function.
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where $\mathrm{dist}_{\mathbb{Z}}$ denotes the [[distance to integers]] function.
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=Properties=
 
=Properties=
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[[Takagi function is continuous]]<br />
<strong>Theorem:</strong> The Takagi function is [[continuous]] on $\mathbb{R}$.
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[[Takagi function is nowhere differentiable]]<br />
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<strong>Proof:</strong>
 
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<strong>Theorem:</strong> The Takagi function is [[nowhere differentiable]] on $\mathbb{R}$.
 
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<strong>Proof:</strong> █
 
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=See Also=
 
=See Also=
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[https://pure.ltu.se/ws/files/30923977/LTU-EX-03320-SE.pdf]<br />
 
[https://pure.ltu.se/ws/files/30923977/LTU-EX-03320-SE.pdf]<br />
 
[http://www.math.tamu.edu/~tvogel/gallery/node7.html]<br />
 
[http://www.math.tamu.edu/~tvogel/gallery/node7.html]<br />
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[[Category:SpecialFunction]]
 
[[Category:SpecialFunction]]

Latest revision as of 03:33, 6 July 2016

The Takagi function (also called the blancmange function) is defined by $$\mathrm{takagi}(x)=\displaystyle\sum_{k=0}^{\infty} \dfrac{\mathrm{dist}_{\mathbb{Z}}(2^n x)}{2^n},$$ where $\mathrm{dist}_{\mathbb{Z}}$ denotes the distance to integers function.

Properties

Takagi function is continuous
Takagi function is nowhere differentiable

See Also

van der Waerden function

References

[1]
[2]

Continuous nowhere differentiable functions