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Finite Field elements in terms of powers of a generator #10971

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adeines mannequin opened this issue Mar 21, 2011 · 4 comments
Closed

Finite Field elements in terms of powers of a generator #10971

adeines mannequin opened this issue Mar 21, 2011 · 4 comments

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@adeines
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Mannequin

adeines mannequin commented Mar 21, 2011

For large values of q, a prime power, GF(q) has elements represented as polynomials over a generator.

sage: F.<a> = GF(2^8)
sage: a^10
a^6 + a^5 + a^4 + a^2

If you further want to compute in a polynomial ring over F, then the polynomials aren't very pretty as they are polynomials with polynomial coefficients.

sage: R.<x> = F[]
sage: a^10*x+1
(a^6 + a^5 + a^4 + a^2)*x + 1

It would be nice to be able to be able to print and work with the elements as powers of the generator.

Component: finite rings

Keywords: GF, finite field

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/10971

@adeines adeines mannequin added this to the sage-5.11 milestone Mar 21, 2011
@adeines adeines mannequin added c: group theory labels Mar 21, 2011
@adeines adeines mannequin assigned wdjoyner Mar 21, 2011
@sagetrac-lmartel
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sagetrac-lmartel mannequin commented Mar 21, 2011

comment:1

But I expect it to be slow...
How would you compute this efficiently?

sage: K.<a> = GF(17**17)
sage: a + 1
a^24137569    # this would be the result in your representation

@jdemeyer jdemeyer modified the milestones: sage-5.11, sage-5.12 Aug 13, 2013
@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.1, sage-6.2 Jan 30, 2014
@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.2, sage-6.3 May 6, 2014
@sagetrac-vbraun-spam sagetrac-vbraun-spam mannequin modified the milestones: sage-6.3, sage-6.4 Aug 10, 2014
@jdemeyer

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@jdemeyer
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Reviewer: Jeroen Demeyer

@jdemeyer
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comment:8

This requires discrete log computations, which is too inefficient in general.

Close as "wontfix".

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