#5443: [with patch, needs work] Segfault in congruence subgroup element code
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Reporter: craigcitro | Owner: craigcitro
Type: defect | Status: new
Priority: blocker | Milestone: sage-3.4
Component: modular forms | Keywords:
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Comment(by davidloeffler):
Hi Craig,
Thanks for looking at this so quickly; but as I mentioned in my email to
sage-devel, the problem doesn't occur under pre-3.3 versions because the
output of Gamma0(2).gens() isn't the same. In 3.3 and 3.4, the matrices
returned by Gamma0(2).gens() *should* satisfy r**(-1) * u**(-1) == t.
In 3.4 with congroup_element's __cmp__ changed to _cmp_ as in your patch,
it no longer segfaults; but the answer is False, even though the matrices
have the same entries, which isn't great either. And one gets the same
crash as before by doing
sage: (r**(-1) * u**(-1)).matrix() == t.matrix()
So I'm afraid I'm giving this a "needs work". I will do some further
tinkering myself tomorrow.
David
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5443#comment:2>
Sage <http://sagemath.org/>
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