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Difference between revisions of "Class of differentiability"

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''smoothness class <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223802.png" />, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223803.png" />''
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''smoothness class $C^k$, $0\leq k\leq\infty, a$''
  
A concept characterizing differentiable mappings (in particular, functions). The class <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223804.png" /> consists of all continuous functions, the class <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223805.png" /> consists of functions with continuous derivatives of all orders not exceeding <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223806.png" /> (in particular, <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223807.png" /> is the class of functions with continuous derivatives of all orders), and the class <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223808.png" /> consists of all real-analytic functions.
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A concept characterizing differentiable mappings (in particular, functions). The class $C^0$ consists of all continuous functions, the class $C^k$ consists of functions with continuous derivatives of all orders not exceeding $k$ (in particular, $C^\infty$ is the class of functions with continuous derivatives of all orders), and the class $C^a$ consists of all real-analytic functions.
  
  
  
 
====Comments====
 
====Comments====
The notation <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c0223809.png" /> (<img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c02238010.png" /> for analytic) is somewhat unusual. Instead one mostly uses <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c02238011.png" /> (<img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/c/c022/c022380/c02238012.png" /> denotes the first transfinite ordinal number).
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The notation $C^a$ ($a$ for analytic) is somewhat unusual. Instead one mostly uses $C^\omega$ ($\omega$ denotes the first transfinite ordinal number).

Latest revision as of 08:35, 19 April 2014

smoothness class $C^k$, $0\leq k\leq\infty, a$

A concept characterizing differentiable mappings (in particular, functions). The class $C^0$ consists of all continuous functions, the class $C^k$ consists of functions with continuous derivatives of all orders not exceeding $k$ (in particular, $C^\infty$ is the class of functions with continuous derivatives of all orders), and the class $C^a$ consists of all real-analytic functions.


Comments

The notation $C^a$ ($a$ for analytic) is somewhat unusual. Instead one mostly uses $C^\omega$ ($\omega$ denotes the first transfinite ordinal number).

How to Cite This Entry:
Class of differentiability. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Class_of_differentiability&oldid=16922
This article was adapted from an original article by M.I. Voitsekhovskii (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article