#5792: Dirichlet character bug
---------------------------+------------------------------------------------
Reporter: davidloeffler | Owner: craigcitro
Type: defect | Status: new
Priority: major | Milestone:
Component: modular forms | Keywords: dirichlet characters
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This is pretty worrying:
{{{
sage: half_integral_weight_modform_basis(trivial_character(16), 9, 10)
---------------------------------------------------------------------------
KeyError Traceback (most recent call
last)
/home/david/.sage/temp/groke/13438/_home_david__sage_init_sage_0.py in
<module>()
/home/david/sage-3.4.1.rc2/local/lib/python2.5/site-
packages/sage/modular/modform/half_integral.pyc in
half_integral_weight_modform_basis(chi, k, prec)
115 chi = chi.minimize_base_ring()
116 psi = chi.parent()(DirichletGroup(4, chi.base_ring()).gen())
--> 117 eps = chi*psi**((k+1) // 2)
118 eps = eps.minimize_base_ring()
119 M = constructor.ModularForms(eps, (k+1)//2)
/home/david/sage-3.4.1.rc2/local/lib/python2.5/site-
packages/sage/modular/dirichlet.pyc in __pow__(self, n)
463 [1, -1]
464 """
--> 465 return DirichletCharacter(self.parent(), n *
self.element(), check=False)
466
467 def _repr_(self):
/home/david/sage-3.4.1.rc2/local/lib/python2.5/site-
packages/sage/modular/dirichlet.pyc in element(self)
1447 M = P._module
1448 dlog = P._zeta_dlog
-> 1449 v = M([dlog[x] for x in self.values_on_gens()])
1450 self.__element = v
1451 return v
KeyError: -1
}}}
So something is going a bit wrong when multiplying trivial_character(16)
by another character.
I thought I had fixed this one, as part of #5648: there was a bug with
arithmetic operations on characters whose parents had the same moduli but
different zeta orders. But it looks like it isn't fixed after all.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/5792>
Sage <http://sagemath.org/>
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