#1956: implement multivariate truncated power series arithmetic
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Reporter: was
| Owner: pernici
Type: enhancement
| Status: needs_review
Priority: major
| Milestone: sage-4.6.2
Component: commutative algebra
| Keywords: multivariate power series
Author: Niles Johnson
| Upstream: N/A
Reviewer: Martin Albrecht, Simon King
| Merged:
Work_issues: multivariate series on 1 generator should remain different from a
univariate series |
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Comment(by pernici):
I get some strange behaviour; I want to use the reduce method for a
polynomial extracted from a multivariate series
{{{
sage: S.<x,y> = QQ[[]]
sage: p = (1+x+y)^3
sage: pp = p.polynomial()
sage: R = S._poly_ring()
sage: xv = R.gens()
sage: pp.reduce([xv[0]^2,xv[1]^2])
1
}}}
while the expected behavior is as working directly with polynomials
{{{
sage: R.<x,y> = QQ[]
sage: p = (1+x+y)^3
sage: p.reduce([x^2,y^2])
6*x*y + 3*x + 3*y + 1
}}}
After some trials I got the expected result by creating a new ring
and casting the polynomial with it.
{{{
sage: S.<x,y> = QQ[[]]
sage: p = (1+x+y)^3
sage: pp = p.polynomial()
sage: R = PolynomialRing(QQ,S.variable_names())
sage: xv = R.gens()
sage: pp = R(pp)
sage: pp.reduce([xv[0]^2,xv[1]^2])
6*x*y + 3*x + 3*y + 1
}}}
This is unsatisfactory because it should not be necessary to introduce
a new MPolynomial_libsingular ring, and cast the polynomial.
Am I doing something wrong or is there a bug?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/1956#comment:82>
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