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Nov 13, 2015, 2:28:24 PM11/13/15

to libsingular-devel

Dear all,

It seems the following commit:

https://github.com/Singular/Sources/commit/d711b46eb29f241f3854ae99e8451d3beb7f96e4

makes r->pLDeg be switched from a weighted total order to a standard total order when the order is a matrix order with a zero in the first row.

Excuse me if I say stupid things as I have no idea to what extent such an order would make sense, but is it intentional?

Best,

JP

It seems the following commit:

https://github.com/Singular/Sources/commit/d711b46eb29f241f3854ae99e8451d3beb7f96e4

makes r->pLDeg be switched from a weighted total order to a standard total order when the order is a matrix order with a zero in the first row.

Excuse me if I say stupid things as I have no idea to what extent such an order would make sense, but is it intentional?

Best,

JP

Nov 16, 2015, 9:15:28 AM11/16/15

to libsingu...@googlegroups.com

ordering (which is quite useful) and can be represented as diagonal

matrix - which has many zeros in the first row.

If a weigted ordering assigns positive weights to all variables

it is usually the best to use these weight for ecart etc.,

but if weights of different signs or weight 0 exist they cannot be used for the

ecart (requirement: there are only finitely many monomials of a each degree).

Hannes

Nov 17, 2015, 8:59:27 AM11/17/15

to libsingular-devel

I'm sorry, but I have no clue what ecart is :)

Though I spotted it was mentioned as the reason for this commit.

So my question is now:

how to get a polynomial degree using the original degree function used during the polynomial ring creation?

Would using r->pFDegOrig be ok?

(I'm sorry, I'm basically discovering Singular's internals while updating Singular in Sage.)

Best,

JP

Though I spotted it was mentioned as the reason for this commit.

So my question is now:

how to get a polynomial degree using the original degree function used during the polynomial ring creation?

Would using r->pFDegOrig be ok?

(I'm sorry, I'm basically discovering Singular's internals while updating Singular in Sage.)

Best,

JP

Hannes

Nov 17, 2015, 11:47:29 AM11/17/15

to libsingu...@googlegroups.com

On Tue, Nov 17, 2015 at 05:59:26AM -0800, Jean-Pierre Flori wrote:

> I'm sorry, but I have no clue what ecart is :)

> Though I spotted it was mentioned as the reason for this commit.

>

> So my question is now:

> how to get a polynomial degree using the original degree function used

> during the polynomial ring creation?

> Would using r->pFDegOrig be ok?

> (I'm sorry, I'm basically discovering Singular's internals while updating

> Singular in Sage.)

>

> Best,

> JP

there is:
> I'm sorry, but I have no clue what ecart is :)

> Though I spotted it was mentioned as the reason for this commit.

>

> So my question is now:

> how to get a polynomial degree using the original degree function used

> during the polynomial ring creation?

> Would using r->pFDegOrig be ok?

> (I'm sorry, I'm basically discovering Singular's internals while updating

> Singular in Sage.)

>

> Best,

> JP

r->pFDeg : the degree of the leading monomial, compatible with the

ordering

r->pLDeg : the maximal degree (and the length) of a polynomial,

usable for ecart

p_WDegree/pWDegree: degree of the leading monomial wrt. the current

weights, total degree for lex. orderings

p_Deg/pDeg: degree of the leading monomial wrt. the current weights

p_Totaldegree/pTotaldegree: degree of the leading monomial wrt. weight 1

Remark: ecart:=max degree - degree of leading term,

used for non-global orderings (i.e. algorithm of Mora)

Hannes

Nov 17, 2015, 6:11:33 PM11/17/15

to libsingu...@googlegroups.com

On Tue, Nov 17, 2015 at 05:47:24PM +0100, han...@mathematik.uni-kl.de wrote:

> there is:

> r->pFDeg : the degree of the leading monomial, compatible with the

> ordering

> r->pLDeg : the maximal degree (and the length) of a polynomial,

> usable for ecart

> p_WDegree/pWDegree: degree of the leading monomial wrt. the current

> weights, total degree for lex. orderings

> p_Deg/pDeg: degree of the leading monomial wrt. the current weights

> p_Totaldegree/pTotaldegree: degree of the leading monomial wrt. weight 1

>

> Remark: ecart:=max degree - degree of leading term,

> used for non-global orderings (i.e. algorithm of Mora)

>

> Hannes

Addendum:
> there is:

> r->pFDeg : the degree of the leading monomial, compatible with the

> ordering

> r->pLDeg : the maximal degree (and the length) of a polynomial,

> usable for ecart

> p_WDegree/pWDegree: degree of the leading monomial wrt. the current

> weights, total degree for lex. orderings

> p_Deg/pDeg: degree of the leading monomial wrt. the current weights

> p_Totaldegree/pTotaldegree: degree of the leading monomial wrt. weight 1

>

> Remark: ecart:=max degree - degree of leading term,

> used for non-global orderings (i.e. algorithm of Mora)

>

> Hannes

r->pFDeg is used for ecart, i.e. ignores the weights from the ordering

in the cases there r->pLDeg ignores them: if not all weights are

positive (resp. of the same sign)

r->pFDegOrig and r->pLdegOrig are never called, but just the original

settings of pFdef/pLDEg if the degree function are temporarily changed

Hannes

Nov 18, 2015, 4:14:11 AM11/18/15

to libsingular-devel

Thanks.

The right solution for me was simply pDeg. Not sure why pLDeg was used in Sage before.

The right solution for me was simply pDeg. Not sure why pLDeg was used in Sage before.

Jun 12, 2016, 9:11:02 PM6/12/16

to libsingular-devel

Am Mittwoch, 18. November 2015 10:14:11 UTC+1 schrieb Jean-Pierre Flori:

Thanks.

The right solution for me was simply pDeg. Not sure why pLDeg was used in Sage before.

I'm not sure that is right.

@Hans

consider following example:

`ring rng = 0,(x,y), lp;`

poly p = x;

deg(x);

when I use p_Deg() to compute the degree of x instead of pLDeg, I get

65536 as an answer. Why?

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