OK, this is now trac #4352. I should be able to do this in the next
couple of months at the latest.
-Marshall Hampton
On Oct 23, 3:15 pm, Marshall Hampton <[EMAIL PROTECTED]> wrote:
> Hi Ursula,
>
> This is not currently supported by Sage in an easy way. Since you are
> interested (and I am too now), I will file a ticket for an
> enhancement, but I don't have time to work on it right away.
>
> I can give you an example of how to do it in a crude way:
>
> r.<x,y> = PolynomialRing(QQ,2)
> fg = r.ideal([x^2-y,y^4-x]).groebner_fan()
> from subprocess import *
> gfan_processes = Popen(['gfan','_weightvector','-m'],stdin = PIPE,
> stdout=PIPE, stderr=PIPE)
> ans, err = gfan_processes.communicate(input = fg.gfan())
> print ans
>
> will return
>
> {
> (5,1),
> (3,1),
> (1,3)}
>
> which I presume are the weight vectors corresponding to the three
> reduced Groebner bases in this example.
>
> On Oct 23, 2:18 pm, Ursula Whitcher <[EMAIL PROTECTED]>
> wrote:
>
> > I asked Anders Jensen, "I would like to compute the weight vectors
> > corresponding to each reduced Groebner basis in gfan's output. Is
> > there a way to tell gfan to do this?"
>
> > He replied:
>
> > "There is a command "weightvector" that does exactly this. The command
> > is hidden (does not show up in the manual or the file system). To run
> > it type "gfan _weightvector" in your shell. MIND THE SPACE BEFORE '_'.
> > According to the --help text the correct thing to do would be to run
> > "gfan _weightvector -m" with the gfan output as input.
>
> > For example
> > gfan | gfan _weightvector -m
> > Q[x,y]
> > {x-y}
>
> > will produce a list of two vectors.
> > I hope this works out for you.
> > Best regards,
> > Anders"
>
> > Is there a way to access the weightvector command from the Sage
> > implementation of gfan?
>
> > Thanks!
> > Ursula
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