#10716: Adding a weighted_degree function to Singular multivariate polynomials
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Reporter: jsrn | Owner: AlexGhitza
Type: enhancement | Status: needs_work
Priority: minor | Milestone: sage-6.3
Component: algebraic | Resolution:
geometry | Merged in:
Keywords: multivariate | Reviewers: Marshall Hampton
polynomials,degree,Singular | Work issues:
Authors: Johan S. R. | Commit:
Nielsen, Luis Felipe Tabera | 3155491ca8a1c32a5245d7f659ff90cb97aba2ff
Alonso | Stopgaps:
Report Upstream: N/A |
Branch: |
u/lftabera/weighted_degree |
Dependencies: |
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Changes (by lftabera):
* status: needs_review => needs_work
Comment:
The conversion is the other way around, from int to Integer. You are right
that there is a performance penalty. I do not have the numbers at hand
right now but I will look at it and check if there is a more clever way.
The method is not cached in any way, the degree is computed any time that
the method is called.
If the user want to use a ring that is mapped to singular as is worried
about performance, because it will call the method a lot of times or over
huge polynomials, the recommendation in the documentation is to create a
ring with that term order and then just call degree inside that ring. It
will be orders of magnitude faster. That is, this method is intended to
use for a weighted degree different from the one in the base ring.
I have found further problems with the patch:
The patch is intended to work over every multivariate polynomial ring out
there. But generic multivariate rings do not have an as_Etuple option in
the exponents method. This means that the exponents are ETuples by default
and I cannot use as_ETuple. This will impose a performance penalty greater
than the int to Integer conversion.
The degree in generic multivariate rings do not return the weighted
degree. This is a bug in my opinion. Because it makes sage non consistent.
This is for another ticket.
--
Ticket URL: <http://trac.sagemath.org/ticket/10716#comment:29>
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