Hi Burcin,

Many thanks!
I see that with this patches, it would be esasy to have also a Weyl
algebra implementation in Sage

Cheers,
Pablo

On Mon, Oct 24, 2011 at 10:11 AM, Burcin Erocal <bur...@erocal.org> wrote:
> Hi Pablo,
>
> On Sat, 22 Oct 2011 18:49:39 -0300
> Pablo De Napoli <pden...@gmail.com> wrote:
>
>> On Thu, Oct 20, 2011 at 6:02 PM, Pablo De Napoli <pden...@gmail.com>
>> wrote:
>> > Hi,
>> >
>> > I need to perform computations with linear differential operators
>> > whose coefficients are polynomials
>> > in several variables (in Euclean space).
>> > Has Sage some support for this kind of computation?
>> >
>> > Could you suggest me some tool for doing that?
>> >
>> > For instance assume that you have two first order differentian
>> > operators (vector fields in the language of differential geometry)
>> > like
>> >
>> > X = x D_x - y D_y
>> >
>> > Y= x D_x - y D_z
>> >
>> > where D_x is the partial derivative with respect to x. I would like
>> > to compute XY
>> > [which is a second order operator], or things like the Lie bracket
>> > [X,Y]=XY-YX) [which is a first order one]
>
> You can also do this in Sage, after applying the patches at #4539:
>
> http://trac.sagemath.org/sage_trac/ticket/4539
>
> This is a generic interface to the noncommutative part of Singular.
>
> http://www.singular.uni-kl.de/Manual/latest/sing_387.htm#SEC427
>
> sage: F.<x,y,z,dx,dy,dz> = FreeAlgebra(QQ, 6)
> sage: G = F.g_algebra({dx*x: x*dx + 1, dy*y: y*dy + 1, dz*z: z*dz + 1})
> sage: G.inject_variables()
> Defining x, y, z, dx, dy, dz
> sage: X = x*dx - y*dy
> sage: Y = x*dx - y*dz
> sage: X*Y
> x^2*dx^2 - x*y*dx*dy - x*y*dx*dz + y^2*dy*dz + x*dx + y*dz
> sage: X*Y - Y*X
> y*dz
>
>
> Cheers,
> Burcin
>

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