[sage-support] associated_primes broken with term order invlex

2010-02-10 Thread Stefan Boettner
Hello, since I changed to version 4.3.2 it seems that calling associated_primes() on an ideal of a polynomial ring that has term order 'invlex' is broken. Example: sage: R.x,y=PolynomialRing(QQ,2,order='invlex') sage: R.ideal(x).associated_primes() ? // Not implemented for this ordering, please

[sage-support] cancellation in fraction fields

2010-01-24 Thread Stefan Boettner
Hi, I'm working with fraction fields of multivariate polynomials ring with coefficients in Q. My question is, how do I get cancellation between numerator and denominator coefficients to work? Example: R.x,y=PolynomialRing(QQ, 2) F=FractionField(R) f=(x/2)/(y/2) My question is, how do I get

Re: [sage-support] Re: cancellation in fraction fields

2010-01-24 Thread Stefan Boettner
That sort of gets my expressions nicer. It doesn't quite solve the issue with the computation time but works for now. Would it be too difficult to have such fractions normalized automatically to some normal form, e.g. monic denominator polynomial, if the coefficient ring is a field? Thanks,

[sage-support] Factoring multivariate polynomials with parameters

2009-11-28 Thread Stefan Boettner
Hello, I would like to factor multivariate polynomials that have parameters in the coefficient field, for example: K.a=PolynomialRing(QQ,1) K=FractionField(K) R.x,y=PolynomialRing(K,2) Now I would like to factor elements in R, such as x^2-m^2*y^2, which actually works. However, when I ask

Re: [sage-support] Factoring multivariate polynomials with parameters

2009-11-28 Thread Stefan Boettner
expect that factoring just x is also implemented? Maybe it's also just a bug. If I replace the definition of the ring R by R.x,y,a=PolynomialRing(QQ,3) then all four examples work correctly. Stefan Am 28.11.2009 um 17:17 schrieb William Stein: On Sat, Nov 28, 2009 at 3:06 PM, Stefan Boettner

[sage-support] Symbolic Expression

2009-09-15 Thread Stefan Boettner
Hello, I'm trying to parse symbolic expressions, but got stuck very quickly. If I say: (x^2).operator() I get: built-in function pow If I say: pow I also get: built-in function pow But if I say: (x^2).operator()==pow I get: False How do I properly test if the topmost operation of an

[sage-support] Re: Symbolic Expression

2009-09-15 Thread Stefan Boettner
That helps for now. Thanks, Stefan Am 15.09.2009 um 22:19 schrieb Nils Bruin: On Sep 15, 6:24 pm, Stefan Boettner sboet...@tulane.edu wrote: Hello, I'm trying to parse symbolic expressions, but got stuck very quickly. If I say: (x^2).operator() I get: built-in function pow If I