Thanks Marc for your answer! It would be very useful to have explicitely
mentioned in the documentation of these functions that the result is not
constant over time (ie explain what consistency the user is supposed to
expect). Looking at the name "is_ordinary", I do not suspect it to be
dependent on the random seed.
Best,
Vincent
On 15/05/2017 19:02, Marc Masdeu wrote:
The function ps_modsym_from_simple_modsym_space calls internally a
randomized method from modular symbols (dual_eigenvector). Here is a
snippet of code that also returns different answers depending on the seed
(on a fresh session, since dual_eigenvector gets cached).
f = Newforms(32, 8, names='a')[1]
A = f.modular_symbols(1)
w = A.dual_eigenvector()
K = w.base_ring()
print K.defining_polynomial()
The easy solution is to change the doctest in pollack_stevens' code. Here
is a solution that would work:
A number field example. Here there are multiple primes above `p`,
and
`\phi` is ordinary at one but not the other.::
sage: f = Newforms(32, 8, names='a')[1]
sage: K = f.hecke_eigenvalue_field()
sage: a = f[3]
sage: from sage.modular.pollack_stevens.space import
ps_modsym_from_simple_modsym_space
sage: phi =
ps_modsym_from_simple_modsym_space(f.modular_symbols(1))
sage: phi.is_ordinary(K.ideal(3, 1/16*a + 3/2)) !=
phi.is_ordinary(K.ideal(3,
1/16*a + 5/2))
True
sage: phi.is_ordinary(3)
Traceback (most recent call last):
...
TypeError: P must be an ideal
On Monday, May 15, 2017 at 3:57:21 PM UTC+2, vdelecroix wrote:
Dear all,
I am worried about a consequence of my cleaning in matrix_rational_dense
at [1]. It appears that an innocent doctest in
modular/pollack_stevens/modsym.py depends on the seed of the random
generators where it should not be, see [2]. I tested a lot more than it
used to be the code in matrix_rational_dense and I did not detect
anything wrong there.
If nobody knows how to fix it, I propose to quickly add a stopgap in the
corresponding functions in sage/modular.
Best,
Vincent
[1] https://trac.sagemath.org/ticket/22970
[2] https://trac.sagemath.org/ticket/22970#comment:14
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