#14489: _S_class_group_and_units is mathematically incorrect
---------------------------------+------------------------------------------
Reporter: robharron | Owner: davidloeffler
Type: defect | Status: needs_work
Priority: critical | Milestone: sage-5.11
Component: number fields | Resolution:
Keywords: S-class group | Work issues:
Report Upstream: N/A | Reviewers: Peter Bruin
Authors: Robert Harron | Merged in:
Dependencies: | Stopgaps:
---------------------------------+------------------------------------------
Changes (by jdemeyer):
* status: positive_review => needs_work
Comment:
On 32-bit systems:
{{{
sage -t devel/sage/sage/rings/polynomial/polynomial_quotient_ring.py
**********************************************************************
File "devel/sage/sage/rings/polynomial/polynomial_quotient_ring.py", line
987, in
sage.rings.polynomial.polynomial_quotient_ring.PolynomialQuotientRing_generic.S_class_group
Failed example:
S.S_class_group([])
Expected:
[((1/4*xbar^2 + 31/4, (-1/8*a + 1/8)*xbar^2 - 31/8*a + 31/8,
1/16*xbar^3 + 1/16*xbar^2 + 31/16*xbar + 31/16, -1/16*a*xbar^3 + (1/16*a +
1/8)*xbar^2 - 31/16*a*xbar + 31/16*a + 31/8), 6, 1/16*xbar^3 - 5/16*xbar^2
+ 31/16*xbar - 139/16), ((-1/4*xbar^2 - 23/4, (1/8*a - 1/8)*xbar^2 +
23/8*a - 23/8, -1/16*xbar^3 - 1/16*xbar^2 - 23/16*xbar - 23/16,
1/16*a*xbar^3 + (-1/16*a - 1/8)*xbar^2 + 23/16*a*xbar - 23/16*a - 23/8),
6, 1/16*xbar^3 + 3/16*xbar^2 + 23/16*xbar + 85/16), ((-5/4*xbar^2 - 115/4,
5/4*a*xbar^2 + 115/4*a, -5/16*xbar^3 + 5/16*xbar^2 - 115/16*xbar + 115/16,
1/16*a*xbar^3 + 7/16*a*xbar^2 + 23/16*a*xbar + 161/16*a), 2, 5/16*xbar^3 +
37/16*xbar^2 + 115/16*xbar + 867/16)]
Got:
[((1/4*xbar^2 + 31/4, (-1/8*a + 1/8)*xbar^2 - 31/8*a + 31/8,
1/16*xbar^3 + 1/16*xbar^2 + 31/16*xbar + 31/16, -1/16*a*xbar^3 + (1/16*a +
1/8)*xbar^2 - 31/16*a*xbar + 31/16*a + 31/8), 6, -1/16*xbar^3 +
1/16*xbar^2 - 31/16*xbar + 47/16), ((-1/4*xbar^2 - 23/4, (1/8*a -
1/8)*xbar^2 + 23/8*a - 23/8, -1/16*xbar^3 - 1/16*xbar^2 - 23/16*xbar -
23/16, 1/16*a*xbar^3 + (-1/16*a - 1/8)*xbar^2 + 23/16*a*xbar - 23/16*a -
23/8), 6, 1/16*xbar^3 + 3/16*xbar^2 + 23/16*xbar + 85/16), ((-5/4*xbar^2 -
115/4, 5/4*a*xbar^2 + 115/4*a, -5/16*xbar^3 + 5/16*xbar^2 - 115/16*xbar +
115/16, 1/16*a*xbar^3 + 7/16*a*xbar^2 + 23/16*a*xbar + 161/16*a), 2,
5/16*xbar^3 + 37/16*xbar^2 + 115/16*xbar + 867/16)]
**********************************************************************
File "devel/sage/sage/rings/polynomial/polynomial_quotient_ring.py", line
1063, in
sage.rings.polynomial.polynomial_quotient_ring.PolynomialQuotientRing_generic.class_group
Failed example:
S.class_group()
Expected:
[((2, -a + 1, 1/2*xbar + 1/2, -1/2*a*xbar + 1/2*a + 1), 6, -1/2*xbar +
3/2)]
Got:
[((2, -a + 1, 1/2*xbar + 1/2, -1/2*a*xbar + 1/2*a + 1), 6, 1/2*xbar -
3/2)]
**********************************************************************
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14489#comment:16>
Sage <http://www.sagemath.org>
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