IMHO this is borderline between devel and support - it is about extending
Sage interface to Macaulay2 with a new type.
On Monday, July 4, 2016 at 6:08:48 PM UTC+1, vdelecroix wrote:
>
> Could this kind of discussion can be done on sage-support? As it name
> suggests sage-devel is dedicated to development discussions. If we want
> to keep developers reading it, it is better to not flood it with users
> usage questions.
>
> On 02/07/16 14:13, saad khalid wrote:
> > Hey everyone:
> >
> > I was hoping some of you could provide some insight where my knowledge
> is
> > lacking. I'm trying to add to the M2/Sage interface by adding a
> conversion
> > for the M2 Divide class. Sage can already convert polynomials, so my
> hope
> > was to just have it treat the Divide class as two polynomials, one in
> the
> > numerator and the other in the denominator. Here is an example of an
> object
> > in the divide class:
> > macaulay2.eval("""
> > K = toField(QQ[zet]/(zet^8 - zet^7 +zet^5 - zet^4 +zet^3 -zet + 1))
> > A=matrix{{zet^1,0},{0,zet^13}}
> > needsPackage "InvariantRing"
> > G=generateGroup({A},K)
> > P = molienSeries G
> > """)
> >
> > P is a "Divide" object. Here is an example of Sage converting a
> polynomial
> > from M2 to Sage:
> > macaulay2.eval("""
> > needsPackage "Points";
> > M = matrix{{1,2,3},{4,5,6}}
> > R = QQ[x,y,MonomialOrder=>Lex];
> > (Q,inG,G) = points(M,R)
> > G#0
> > ring G#0
> > """)
> > G0 = macaulay2('G#0').to_sage(); G0
> >
> > G in M2 is a list of polynomials, and G#0 is the first one. Here's what
> it
> > looks like:
> >
> > 3 2
> > y - 15y + 74y - 120
> >
> > I convert this to a sage object, G0, and it appears as:
> >
> > y^3 - 15*y^2 + 74*y - 120
> >
> > The part that I really need is where Sage changes M2's two-line display
> for exponents on variables to just the standard Sage notation. I'm looking
> at the to_sage()
> > method in the source code but I can't seem to figure out how it's doing
> it. Am I missing something obvious? G#0 is a polynomial ring I believe, and
> here
> > is the code in the to_sage function for PolynomialRings:
> > elif cls_str == "PolynomialRing":
> > from sage.rings.all import PolynomialRing
> > from sage.rings.polynomial.term_order import
> inv_macaulay2_name_mapping
> >
> > #Get the base ring
> > base_ring = self.coefficientRing().to_sage()
> >
> > #Get a string list of generators
> > gens = str(self.gens())[1:-1]
> >
> > # Check that we are dealing with default degrees, i.e.
> 1's.
> > if self.degrees().any("x -> x != {1}").to_sage():
> > raise ValueError("cannot convert Macaulay2
> polynomial ring with non-default degrees to Sage")
> > #Handle the term order
> > external_string = self.external_string()
> > order = None
> > if "MonomialOrder" not in external_string:
> > order = "degrevlex"
> > else:
> > for order_name in inv_macaulay2_name_mapping:
> > if order_name in external_string:
> > order =
> inv_macaulay2_name_mapping[order_name]
> > if len(gens) > 1 and order is None:
> > raise ValueError("cannot convert Macaulay2's term
> order to a Sage term order")
> >
> > return PolynomialRing(base_ring, order=order,
> names=gens)
> >
> >
> > Where in this code does that conversion happen? It's like parsing ascii
> > art...
> >
> > Thanks!
> >
>
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