ah thanks much -- I also just found it by just trial and error.
On Sep 7, 2:39 pm, Jason Grout <[email protected]> wrote: > On 9/7/10 3:34 PM, tvn wrote: > > > > > > > Hi John and Jason, thanks -- the inject_variables() did what I > > want. > > > I have another question below and hope you can help > > > what if I already have create a function call f = x - y as below > > > sage: vs = var('x y') > > sage: f = x - y > > sage: type(f) > > <type 'sage.symbolic.expression.Expression'> > > > now I want to convert f to > > sage.rings.polynomial.multi_polynomial_element.MPolynomial_polydict , > > is there any convenient way to do so ? One way is to define > > variables x,y in PolynomialRing QQ and then redefine f = x-y but it's > > quite inconvenient. > > Try the .polynomial() method: > > sage: var('x,y') > (x, y) > sage: f=x-y > sage: g=f.polynomial(QQ) > sage: g > x - y > sage: type(g) > <type > 'sage.rings.polynomial.multi_polynomial_libsingular.MPolynomial_libsingular '> > sage: g.variables() > (x, y) > sage: g.parent() > Multivariate Polynomial Ring in x, y over Rational Field > > Jason -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
