Can't construct the quotient of an univariate polynomial ring by its zero ideal

[jmbr]

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| Sage Version 3.4.2.rc0, Release Date: 2009-04-30                   |
| Type notebook() for the GUI, and license() for information.        |
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sage: R = QQ['x']
sage: R.quotient(R.zero_ideal())
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

/home/mabshoff/.sage/temp/sage.math.washington.edu/1567/_home_mabshoff__sage_init_sage_0.py in <module>()

/scratch/mabshoff/sage-3.4.2.final/local/lib/python2.5/site-packages/sage/rings/ring.so in sage.rings.ring.CommutativeRing.quotient (sage/rings/ring.c:6627)()

/scratch/mabshoff/sage-3.4.2.final/local/lib/python2.5/site-packages/sage/rings/quotient_ring.pyc in QuotientRing(R, I, names)
    137     try:
    138         if I.is_principal():
--> 139             return R.quotient_by_principal_ideal(I.gen(), names)
    140     except (AttributeError, NotImplementedError):
    141         pass

/scratch/mabshoff/sage-3.4.2.final/local/lib/python2.5/site-packages/sage/rings/polynomial/polynomial_ring.pyc in quotient_by_principal_ideal(self, f, names)
   1092         """
   1093         import sage.rings.polynomial.polynomial_quotient_ring
-> 1094         return sage.rings.polynomial.polynomial_quotient_ring.PolynomialQuotientRing(self, f, names)
   1095     
   1096 

/scratch/mabshoff/sage-3.4.2.final/local/lib/python2.5/site-packages/sage/rings/polynomial/polynomial_quotient_ring.pyc in PolynomialQuotientRing(ring, polynomial, names)
    149     c = polynomial.leading_coefficient()
    150     if not c.is_unit():
--> 151         raise TypeError, "polynomial must have unit leading coefficient"
    152     R = ring.base_ring()
    153     if isinstance(R, sage.rings.integral_domain.IntegralDomain):

TypeError: polynomial must have unit leading coefficient

---

Apply: trac_5978-quotient_zero_ideal-ts.patch

[mabshoff]

Do not attach the error message, but post it verbatim into the ticket.

Also always assign a milestone.

[tscrim]

Fixed by making the quotient by a zero ideal return the original ring.

sage: ZZ.quotient(ZZ.zero_ideal()) is ZZ
True
sage: R = QQ['x']
sage: R.quotient(R.zero_ideal()) is R
True

[tscrim]

Fixed this for quotient_by_principal_ideal() method in polynomial ring as well.

For patchbot:

Apply: trac_5978-quotient_zero_ideal-ts.2.patch

[tscrim]

Fixed other doctests.

For patchbot:

Apply: trac_5978-quotient_zero_ideal-ts.patch

[lftabera]

the patch looks good to me. I have made also further tests. Positive review.

Apply: trac_5978-quotient_zero_ideal-ts.patch

[tscrim]

Thank you for the review.

Travis

[jdemeyer]

Rebased to sage-5.8.beta0.