#4764: Error in computing complement of modular symbol space
---------------------------------+--------------------------
Reporter: robertwb | Owner: craigcitro
Type: defect | Status: closed
Priority: major | Milestone: sage-3.2.2
Component: modular forms | Resolution: duplicate
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Changes (by chapoton):
* upstream: => N/A
Old description:
> {{{
> sage: f = EllipticCurve('128a').modular_symbol_space()
> sage: f.complement()
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File
> "/Users/robert/.sage/sage_notebook/worksheets/admin/110/code/7.py", line
> 7, in <module>
> f.complement()
> File "/Users/robert/sage/current/local/lib/python2.5/site-
> packages/SQLAlchemy-0.4.6-py2.5.egg/", line 1, in <module>
>
> File "/Users/robert/sage/sage-3.1.3/local/lib/python2.5/site-
> packages/sage/modular/hecke/submodule.py", line 202, in complement
> raise RuntimeError, "Computation of complementary space failed (cut
> down to rank %s, but should have cut down to rank %s)."%(V.rank(),
> self.rank())
> RuntimeError: Computation of complementary space failed (cut down to rank
> 18, but should have cut down to rank 1).
> }}}
>
> Note that the error is wrong, as
>
> {{{
> sage: ModularSymbols(128, sign=1)
>
> Modular Symbols space of dimension 18 for Gamma_0(128) of weight 2 with
> sign 1 over Rational Field
> }}}
>
> however, it should have cut the rank down to 17.
New description:
{{{
sage: f = EllipticCurve('128a').modular_symbol_space()
sage: f.complement()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/robert/.sage/sage_notebook/worksheets/admin/110/code/7.py",
line 7, in <module>
f.complement()
File "/Users/robert/sage/current/local/lib/python2.5/site-
packages/SQLAlchemy-0.4.6-py2.5.egg/", line 1, in <module>
File "/Users/robert/sage/sage-3.1.3/local/lib/python2.5/site-
packages/sage/modular/hecke/submodule.py", line 202, in complement
raise RuntimeError, "Computation of complementary space failed (cut
down to rank %s, but should have cut down to rank %s)."%(V.rank(),
self.rank())
RuntimeError: Computation of complementary space failed (cut down to rank
18, but should have cut down to rank 1).
}}}
Note that the error is wrong, as
{{{
sage: ModularSymbols(128, sign=1)
Modular Symbols space of dimension 18 for Gamma_0(128) of weight 2 with
sign 1 over Rational Field
}}}
however, it should have cut the rank down to 17.
--
--
Ticket URL: <http://trac.sagemath.org/ticket/4764#comment:4>
Sage <http://www.sagemath.org>
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