I agree with this (but the documentation should be very clear). It's the same in Magma:
> Type(PolynomialRing(RationalField())); RngUPol > Type(PolynomialRing(RationalField(),1)); RngMPol John On 30/09/2007, William Stein <[EMAIL PROTECTED]> wrote: > > On 9/30/07, Mike Hansen <[EMAIL PROTECTED]> wrote: > > > > > There is something *extremely* fishy about the base ring here! It's > > > a *multivariate* polynomial ring: > > > > Here is the culprit: > > > > sage: type(PolynomialRing(ZZ, 1, 'x')) > > <class > > 'sage.rings.polynomial.multi_polynomial_ring.MPolynomialRing_polydict_domain'> > > > > while > > > > sage: type(PolynomialRing(ZZ, 'x')) > > <class > > 'sage.rings.polynomial.polynomial_ring.PolynomialRing_integral_domain'> > > > > I've created a ticket: http://www.sagetrac.org/sage_trac/ticket/764 > > and will post a patch later on. > > Wait! This would an explicit intentional design choice, not a bug. > I think it should be possible to create ZZ['x'] but as a multivariate > polynomial ring instead of a univariate polynomial ring, > since there are certain things one can do with multivariate > polynomial rings that don't make sense with single variate rings. > > Maybe I'm wrong, since things have been so well developed by now. > I would like some further discussion and input (esp. from Martin Albrecht) > on this before changing anything. > > > > sage: s = hlqp5_m.change_ring(ZZ['x']) > > > sage: time w=s^(-1) > > > CPU times: user 0.10 s, sys: 0.00 s, total: 0.10 s > > > > > > Even 8 works pretty quickly: > > > > > > sage: hlqp8 = [ symmetrica.hall_littlewood(p) for p in Partitions(8) ] > > > sage: hlqp8_m = matrix([[ x.coefficient(p) for p in Partitions(8) ] > > > for x in hlqp8]) > > > sage: s = hlqp8_m.change_ring(ZZ['x']); s > > > 22 x 22 dense matrix over Univariate Polynomial Ring in x over Integer > > > Ring > > > sage: time w=s^(-1) > > > CPU times: user 2.13 s, sys: 0.04 s, total: 2.17 s > > > Wall time: 2.29 > > > sage: time t=s*s > > > CPU times: user 0.24 s, sys: 0.00 s, total: 0.24 s > > > > Those numbers seem much better. > > > > --Mike > > > > > > > > > > -- > William Stein > Associate Professor of Mathematics > University of Washington > http://wstein.org > > > > -- John Cremona --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
