#4513: [with patch, needs review] Action of MatrixGroup on a MPolynomialRing
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Reporter: SimonKing | Owner: SimonKing
Type: enhancement | Status: new
Priority: major | Milestone: sage-3.2.1
Component: commutative algebra | Resolution:
Keywords: matrix group, action, polynomial ring |
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Comment (by wdj):
I did confirm that the patches apply cleanly,
that
{{{
sage: M = Matrix(GF(3),[[1,2],[1,1]])
sage: G = MatrixGroup([M])
sage: g = G.0
sage: g
[1 2]
[1 1]
sage: P.<x,y> = PolynomialRing(GF(3),2)
sage: p = x*y^2
sage: g(p)
x^3 + x^2*y - x*y^2 - y^3
sage: (x+2*y)*(x+y)^2
x^3 + x^2*y - x*y^2 - y^3
}}}
works, and that the code seems well-documented.
However, I can't do testing on this machine
(intrepid ubuntu) and some of the code is written in
Cython, which I can't really 100% vouch for.
Seems okay though and simple enough. Since speed was a
topic of the comments above, my only question is that the
segment
{{{
396 for i from 0<=i<l:
397 X = Expo[i]
398 c = Coef[i]
399 q += c*prod([Im[k]**X[k] for k in xrange(n)])
}}}
could probably be rewritten as a one-line sum, which might
(or might not) be faster.
Maybe Martin Albrecht could comment on the Cython code?
If Martin (for example) passes the Cython code, and the
docstrings pass sage -testall, I would give it a positive review.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4513#comment:8>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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