Fix: Correct divides() for LaurentPolynomialRing elements (closes #40… #40394
Conversation
| r""" | ||
| Return ``True`` if ``self`` divides ``other``. | ||
|
|
||
| EXAMPLES:: | ||
|
|
||
| sage: R.<x> = LaurentPolynomialRing(ZZ) | ||
| sage: (2*x**-1 + 1).divides(4*x**-2 - 1) | ||
| True | ||
| sage: (2*x + 1).divides(4*x**2 + 1) | ||
| False | ||
| sage: (2*x + x**-1).divides(R(0)) | ||
| True | ||
| sage: R(0).divides(2*x ** -1 + 1) | ||
| False | ||
| sage: R(0).divides(R(0)) | ||
| True | ||
| sage: R.<x> = LaurentPolynomialRing(Zmod(6)) | ||
| sage: p = 4*x + 3*x^-1 | ||
| sage: q = 5*x^2 + x + 2*x^-2 | ||
| sage: p.divides(q) | ||
| False | ||
|
|
||
| sage: R.<x,y> = GF(2)[] | ||
| sage: S.<z> = LaurentPolynomialRing(R) | ||
| sage: p = (x+y+1) * z**-1 + x*y | ||
| sage: q = (y^2-x^2) * z**-2 + z + x-y | ||
| sage: p.divides(q), p.divides(p*q) # needs sage.libs.singular | ||
| (False, True) | ||
| """ |
There was a problem hiding this comment.
please do not move these tests.
|
As mentioned in the issue, the problem is with the |
…s for Zmod(4) and Zmod(8) (closes sagemath#40372)
|
did you forget to push your changes? |
|
I have now pushed my latest changes to this pull request. The most recent commit updates the divides() method in polynomial_element.pyx to use division with remainder for rings with zero divisors, as requested. |
No, they are not visible. Something went wrong. Please check again. |
Fix divides() for polynomials over rings with zero divisors (closes #40372)
This PR fixes the divides() method for LaurentPolynomialRing elements. The previous implementation incorrectly delegated to the underlying polynomial ring, which does not handle Laurent monomials or zero divisors correctly.
This PR fixes the divides() method for polynomials over rings with zero divisors (e.g., Zmod(4), Zmod(8)), as requested by reviewers and described by DaveWitteMorris in #40372.
Fixes #40372