Better bug report -- a one-liner breaks in sage-7.5 but worked in
sage-7.4. It's
P.<x,y,z> = PolynomialRing(RR, 3, order='lex'); I =
ideal(x^2+y^2+z^2-1, x^2-y+z^2, x-z); I.groebner_basis()
See
~$ sage-7.4
┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 7.4, Release Date: 2016-10-18 │
│ Enhanced for SageMathCloud. │
└────────────────────────────────────────────────────────────────────┘
sage: P.<x,y,z> = PolynomialRing(RR, 3, order='lex'); I =
ideal(x^2+y^2+z^2-1, x^2-y+z^2, x-z); I.groebner_basis()
[x - z, y - 2.00000000000000*z^2, z^4 + 0.500000000000000*z^2 -
0.250000000000000]
sage:
Exiting Sage (CPU time 0m0.64s, Wall time 0m29.60s).
Exiting Singular with PID 21074 running
/projects/sage/sage-7.4/local/bin/Singular -t --ticks-per-sec 1000
--cntrlc=a
~$ sage-7.5
┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 7.5, Release Date: 2017-01-11 │
│ Enhanced for SageMathCloud. │
└────────────────────────────────────────────────────────────────────┘
sage: P.<x,y,z> = PolynomialRing(RR, 3, order='lex'); I =
ideal(x^2+y^2+z^2-1, x^2-y+z^2, x-z); I.groebner_basis()
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-1-67a484fdc04d> in <module>()
----> 1 P = PolynomialRing(RR, Integer(3), order='lex', names=('x',
'y', 'z',)); (x, y, z,) = P._first_ngens(3); I =
ideal(x**Integer(2)+y**Integer(2)+z**Integer(2)-Integer(1),
x**Integer(2)-y+z**Integer(2), x-z); I.groebner_basis()
/projects/sage/sage-7.5/src/sage/misc/cachefunc.pyx in
sage.misc.cachefunc.CachedMethodCaller.__call__
(/projects/sage/sage-7.5/src/build/cythonized/sage/misc/cachefunc.c:10792)()
2036 return cache[k]
2037 except KeyError:
-> 2038 w = self._instance_call(*args, **kwds)
2039 cache[k] = w
2040 return w
/projects/sage/sage-7.5/src/sage/misc/cachefunc.pyx in
sage.misc.cachefunc.CachedMethodCaller._instance_call
(/projects/sage/sage-7.5/src/build/cythonized/sage/misc/cachefunc.c:10238)()
1912 True
1913 """
-> 1914 return self.f(self._instance, *args, **kwds)
1915
1916 cdef fix_args_kwds(self, tuple args, dict kwds):
/projects/sage/sage-7.5/local/lib/python2.7/site-packages/sage/rings/polynomial/multi_polynomial_ideal.pyc
in groebner_basis(self, algorithm, deg_bound, mult_bound, prot, *args,
**kwds)
3729 except (TypeError, NameError) as msg: # conversion
to Singular not supported
3730 try:
-> 3731 gb =
self._groebner_basis_singular("groebner", deg_bound=deg_bound,
mult_bound=mult_bound, *args, **kwds)
3732 except (TypeError, NameError,
NotImplementedError) as msg: # conversion to Singular not supported
3733 if self.ring().term_order().is_global()
and is_IntegerModRing(self.ring().base_ring()) and not
self.ring().base_ring().is_field():
/projects/sage/sage-7.5/local/lib/python2.7/site-packages/sage/interfaces/singular.pyc
in wrapper(*args, **kwds)
2722 def wrapper(*args, **kwds):
2723 with SingularGBDefaultContext():
-> 2724 return func(*args, **kwds)
2725 return wrapper
/projects/sage/sage-7.5/local/lib/python2.7/site-packages/sage/rings/polynomial/multi_polynomial_ideal.pyc
in _groebner_basis_singular(self, algorithm, *args, **kwds)
1364 R = self.ring()
1365 S =
self._groebner_basis_singular_raw(algorithm=algorithm, *args, **kwds)
-> 1366 S = PolynomialSequence([R(S[i+1]) for i in
range(len(S))], R, immutable=True)
1367 return S
1368
/projects/sage/sage-7.5/local/lib/python2.7/site-packages/sage/rings/polynomial/multi_polynomial_ring.pyc
in __call__(self, x, check)
479 self._singular_().set_ring()
480 try:
--> 481 return x.sage_poly(self)
482 except TypeError:
483 raise TypeError("unable to coerce singular object")
/projects/sage/sage-7.5/local/lib/python2.7/site-packages/sage/interfaces/singular.pyc
in sage_poly(self, R, kcache)
1774 else:
1775 power=1
-> 1776 exp[var_dict[var]]=power
1777
1778 if kcache is None:
KeyError: '(1.000e+00)'
sage:
On Wed, Feb 15, 2017 at 6:22 PM, Matthew Macauley <[email protected]> wrote:
> Typing the following:
>
>
> P.<x,y,z> = PolynomialRing(RR, 3, order='lex'); P
> I = ideal(x^2+y^2+z^2-1, x^2-y+z^2, x-z); I
> B = I.groebner_basis(); B
>
>
> gives a brutal error (type it into SageMathCell and you'll see).
>
>
> Seth Sullivant suggested that it's due to a roundoff error, because it works
> with fields such as "QQ" or "GF(3)", etc. That said, I am 99% sure that it's
> a relatively new error, because I have typed in those exact lines in
> previous semesters (it's from a HW problem that I assigned) and I haven't
> had any prior issues.
>
> --
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--
William (http://wstein.org)
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