MPolynomial_libsingular reports the wrong degree #11652

saraedum · 2011-08-05T17:12:01Z

On sage-4.7: In the following example, the degree with respect to p should be 1 and the degree with respect to q should be 2.

sage: R.<p,q,t> = ZZ[]
sage: poly = p+q^2+t^3
sage: poly = poly.polynomial(t)[0]
sage: poly
q^2 + p
sage: poly.degree(p)
1
sage: poly.degree(q)
1

The issue can be easily worked around:

sage: poly.degree(poly.parent(q))
2

(originally reported on sage-support, see http://groups.google.com/group/sage-support/browse_thread/thread/608bc46e92da2f49/feb54d2384cef583?lnk=gst&q=polynomial#feb54d2384cef583)

Apply

to the sage repository.

Upstream: Reported upstream. No feedback yet.

Component: commutative algebra

Keywords: singular, polynomial, degree, sd35, sd35.5

Work Issues: issue of comment 5 still there

Author: Julian Rueth, William Stein

Branch/Commit: 54604e4

Reviewer: William Stein, Paul Zimmermann, David Roe

Issue created by migration from https://trac.sagemath.org/ticket/11652

The text was updated successfully, but these errors were encountered:

saraedum · 2011-12-21T01:08:39Z

comment:1

In sage-4.8.alpha3 both calls produce degree 1.

saraedum · 2011-12-21T15:14:06Z

Attachment: trac_11652.patch.gz

fixes detection of generators

saraedum · 2011-12-21T15:23:04Z

Changed keywords from singular, polynomial, degree to singular, polynomial, degree, sd35

williamstein · 2011-12-22T19:01:18Z

apply this instead of trac_11652.patch -- it's a rewrite

williamstein · 2011-12-22T19:02:14Z

Reviewer: wstein

williamstein · 2011-12-22T19:02:14Z

comment:4

Attachment: trac_11652-rewrite.patch.gz

I was going to referee this, but instead ended up improving the documentation (a lot) and rewriting the logic a bit. saraedum can you referee the new patch?

williamstein · 2011-12-22T19:02:14Z

Author: saraedum, wstein

zimmermann6 · 2012-01-11T16:54:28Z

comment:5

all doctests pass on top of sage-4.8.alpha6 on x64, however:

sage: R.<p,q,t> = ZZ[]
sage: poly = p+q^2+t^3
sage: poly = poly.polynomial(t)[0]
sage: poly.degree(p)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
...
TypeError: argument must canonically coerce to parent

I don't understand since the documentation says:

sage: poly.degree?
...
Definition:     poly.degree(self, x=None, std_grading=False)
...
       Return the maximal degree of this polynomial in "x", where "x" must
       be one of the generators for the parent of this polynomial.

Indeed p is one of those generators:

sage: p in poly.parent().gens()
True

Thus either the code or the documentation has to be fixed.

Paul

zimmermann6 · 2012-01-11T16:54:28Z

Work Issues: code and docu do not match

zimmermann6 · 2012-01-11T16:54:28Z

Changed author from saraedum, wstein to saraedum, William Stein

zimmermann6 · 2012-01-11T16:54:28Z

Changed keywords from singular, polynomial, degree, sd35 to singular, polynomial, degree, sd35, sd35.5

zimmermann6 · 2012-01-11T16:54:28Z

Changed reviewer from wstein to William Stein, Paul Zimmermann

roed314 · 2012-06-01T17:58:33Z

Changed upstream from Reported upstream. Little or no feedback. to Reported upstream. No feedback yet.

saraedum · 2012-07-19T23:00:43Z

comment:7

The output for the example in the ticket description has changed. However, it's still wrong.

sage: poly
q^2 + p
sage: poly.degree(p)
1
sage: poly.degree(q)
1

saraedum · 2012-07-19T23:27:14Z

comment:8

Attachment: trac_11652_review.patch.gz

Apply trac_11652-rewrite.patch trac_11652_review.patch

saraedum · 2012-07-19T23:27:14Z

Changed author from saraedum, William Stein to Julian Rueth, William Stein

saraedum · 2012-07-19T23:31:13Z

comment:9

Replying to @zimmermann6:

I don't understand since the documentation says:

       Return the maximal degree of this polynomial in "x", where "x" must
       be one of the generators for the parent of this polynomial.

Indeed p is one of those generators:

sage: p in poly.parent().gens()
True

I tried to make the INPUT section a little more precise. But I believe that writing that x 'is' a generator and not only that x '==' a generator would be overdoing it.

Is it acceptable for you this way?

roed314 · 2012-10-15T08:42:46Z

Changed reviewer from William Stein, Paul Zimmermann to William Stein, Paul Zimmermann, David Roe

roed314 · 2012-10-15T08:42:46Z

comment:10

This looks fine to me.

roed314 · 2012-11-01T19:17:30Z

Changed work issues from code and docu do not match to none

roed314 · 2012-11-01T19:19:39Z

comment:15

I've removed the work issues, changed the ticket description and marked it as positive review again. However, Paul originally objected to the documentation, so if he wants to request additional changes he should feel free to return the ticket to needs work. I just marked it as positive review since I thought that his concerns had been addressed and there hadn't been any comments for a few months.

zimmermann6 · 2012-11-02T07:53:23Z

comment:16

I tried the patch on top of Sage 5.3 and got:

sage: R.<p,q,t> = ZZ[]
sage: poly = p+q^2+t^3
sage: poly = poly.polynomial(t)[0]
sage: poly
q^2 + p
sage: poly.degree(p)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

/tmp/<ipython console> in <module>()

/usr/local/sage-5.3/sage/local/lib/python2.7/site-packages/sage/rings/polynomial/multi_polynomial_libsingular.so in sage.rings.polynomial.multi_polynomial_libsingular.MPolynomial_libsingular.degree (sage/rings/polynomial/multi_polynomial_libsingular.cpp:17832)()

TypeError: argument must canonically coerce to parent

Is that normal?

Paul

roed314 · 2012-11-02T17:14:02Z

comment:17

Yes, that's correct. p is in Z[p,q,t], poly is in Z[p,q] and there's no coercion from Z[p,q,t] to Z[p,q].

zimmermann6 · 2012-11-02T17:50:44Z

comment:18

David, for the variables p and q, there is a trivial conversion...

Anyway the issue raised in comment [comment:5] is still there:

sage: poly.degree?
...
       Return the maximal degree of this polynomial in "x", where "x" must
       be one of the generators for the parent of this polynomial.
sage: poly.parent().gens()
(p, q)
sage: poly.degree(p)
...
TypeError: argument must canonically coerce to parent

According to the documentation, this should work.

zimmermann6 · 2012-11-02T17:50:44Z

Work Issues: issue of comment 5 still there

saraedum · 2014-02-26T01:08:28Z

comment:21

Replying to @zimmermann6:

David, for the variables p and q, there is a trivial conversion...

Anyway the issue raised in comment [comment:5] is still there:
sage: poly.degree?
...
       Return the maximal degree of this polynomial in "x", where "x" must
       be one of the generators for the parent of this polynomial.
sage: poly.parent().gens()
(p, q)
sage: poly.degree(p)
...
TypeError: argument must canonically coerce to parent
According to the documentation, this should work.

Probably you did not have the latest patch applied. With the latest patch I get:

   * "x" - (default: "None") a multivariate polynomial which is (or
     coerces to) a generator of the parent of self. If "x" is "None",
     return the total degree, which is the maximum degree of any
     monomial. Note that a matrix term ordering alters the grading of
     the generators of the ring; see the tests below.  To avoid this
     behavior, use either "exponents()" for the exponents themselves,
     or the optional argument "std_grading=False".

saraedum · 2014-02-26T01:08:56Z

Branch: u/saraedum/ticket/11652

saraedum · 2014-02-26T01:11:43Z

Commit: 54604e4

saraedum · 2014-02-26T01:11:43Z

comment:24

Sorry, you were referring to the summary and not to the parameter description. I believe it is acceptable that the summary is slightly imprecise; that's what the parameters' description is for.

New commits:

`7e35305`	`Trac 11652: fixes degree for multivariate libsingular polynomials`
`54604e4`	`Trac 11652: Review patch for the docstring of degree() for multivariate polynomials`

zimmermann6 · 2014-02-26T15:45:21Z

comment:25

all tests pass on top of Sage 6.0 (except one which seems unrelated).
Thus a positive review for me.

Paul

vbraun · 2014-03-03T18:55:35Z

Changed branch from u/saraedum/ticket/11652 to 54604e4

saraedum added c: commutative algebra labels Aug 5, 2011

saraedum assigned malb Aug 5, 2011

saraedum added the s: needs review label Dec 21, 2011

zimmermann6 added s: needs work and removed s: needs review labels Jan 11, 2012

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jdemeyer modified the milestones: sage-5.11, sage-5.12 Aug 13, 2013

sagetrac-vbraun-spam mannequin modified the milestones: sage-6.1, sage-6.2 Jan 30, 2014

saraedum added s: needs review and removed s: needs work labels Feb 26, 2014

zimmermann6 added s: positive review and removed s: needs review labels Feb 26, 2014

vbraun removed the s: positive review label Mar 3, 2014

vbraun closed this as completed in 2330eca Mar 3, 2014

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MPolynomial_libsingular reports the wrong degree #11652

MPolynomial_libsingular reports the wrong degree #11652

saraedum commented Aug 5, 2011

saraedum commented Dec 21, 2011

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williamstein commented Dec 22, 2011

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vbraun commented Mar 3, 2014

MPolynomial_libsingular reports the wrong degree #11652

MPolynomial_libsingular reports the wrong degree #11652

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saraedum commented Aug 5, 2011

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