Polylogarithmic function: Difference between revisions
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{{Short description|Polynomial function with logarithm terms}} |
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{{Distinguish|Polylogarithm}} |
{{Distinguish|Polylogarithm}} |
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: <math>a_k (\log n)^k + \cdots + a_1(\log n) + a_0. </math> |
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: <math>a_k (\log n)^k + a_{k-1} (\log n)^{k-1} + \cdots + a_1(\log n) + a_0. </math> |
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The notation {{math|log{{sup|''k''}}''n''}} is often used as a shorthand for {{math|(log ''n''){{sup|''k''}}}}, analogous to {{math|sin{{sup|2}}''θ''}} for {{math|(sin ''θ''){{sup|2}}}}. |
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In [[computer science]], polylogarithmic functions occur as the [[Big O notation|order]] of [[time complexity|time]] or [[space complexity|memory used]] by some [[algorithm]]s (e.g., "it has polylogarithmic order"). |
In [[computer science]], polylogarithmic functions occur as the [[Big O notation|order]] of [[time complexity|time]] or [[space complexity|memory used]] by some [[algorithm]]s (e.g., "it has polylogarithmic order"). |
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All polylogarithmic functions |
All polylogarithmic functions of {{mvar|n}} are {{math|O(''n''{{sup|''ε''}})}} for every exponent {{math|''ε'' > 0}} (for the meaning of this symbol, see [[small o notation]]), that is, a polylogarithmic function grows more slowly than any positive exponent. This observation is the basis for the [[Soft O notation#Extensions to the Bachmann–Landau notations|soft O notation]] {{math|Õ(''n'')}}. |
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== References == |
== References == |
Revision as of 05:44, 4 July 2022
In mathematics, a polylogarithmic function in n is a polynomial in the logarithm of n,
The notation logkn is often used as a shorthand for (log n)k, analogous to sin2θ for (sin θ)2.
In computer science, polylogarithmic functions occur as the order of time or memory used by some algorithms (e.g., "it has polylogarithmic order").
All polylogarithmic functions of n are O(nε) for every exponent ε > 0 (for the meaning of this symbol, see small o notation), that is, a polylogarithmic function grows more slowly than any positive exponent. This observation is the basis for the soft O notation Õ(n).
References
- Black, Paul E. (2004-12-17). "polylogarithmic". Dictionary of Algorithms and Data Structures. U.S. National Institute of Standards and Technology. Retrieved 2010-01-10.