Hi Kevin,
On 2014-07-27, Kevin Buzzard kevin.m.buzz...@gmail.com wrote:
[I've just build a degree 6 poly. Now let's build a degree 12 one]
sage: h=expand((g.subs(x+2/x))*x^6)
Let's work without the x^6 factor:
sage: g
x^6 + 2*x^3 + x + 1
sage: g.subs(x+2/x).expand()
2/x + 1/x^3 +
Minor remark: if you have defined x to be a polynomial ring generator
then Sage will happily form rational functions without you having to
define new rings:
sage: R.x = GF(3)[]
sage: R
Univariate Polynomial Ring in x over Finite Field of size 3
sage: f = x+1/x
sage: f.parent()
Fraction Field of
On Sun, Jul 27, 2014 at 12:52 PM, John Cremona john.crem...@gmail.com wrote:
Minor remark: if you have defined x to be a polynomial ring generator
then Sage will happily form rational functions without you having to
define new rings:
sage: R.x = GF(3)[]
sage: R
Univariate Polynomial Ring
I don't think we'll ever get SR to operate properly in positive
characteristics; especially because it would allow completely arbitrary
characteristic combinations in the first place, but perhaps the cases below
help in tracking down if we can so something to improve the situation a bit:
sage:
Thanks to everyone who commented. I am a fool. I got tangled up in some
similar sort of situation a few months ago and David Loeffler emailed me to
basically warn me off sage's x and to use anything else instead. I didn't
follow his advice this time because I couldn't get an R.t constructor to
