Request for reviewers: congruence subgroups

[daveloeffler]

Dear Sage number theorists

I apologise for this request, but I'm wondering if I could persuade
any of the Sage number theory regulars to take a look at some of my
patches to the modular forms code. Next week I'll be giving a
conference talk on the algorithm implemented at #10658, computing
local components of modular forms, which has been sitting on trac
awaiting review for 6 months now; it would be great if someone could
take a look at that.

There is a separate sequence of patches (#11598 - #5048 - #10453 -
#11601) which fix some bugs with subgroups of the modular group SL(2,
Z), and add a bunch of new functionality for handing completely
arbitrary congruence subgroups of the modular group (not just the
"standard" subgroups Gamma0(N), Gamma1(N) etc). Tickets #5048 and
#10453 have also both been at "needs review" for a rather long while
(7 months).

Regards, David

[Georg S. Weber]

Hi David,

I see what I can do. A first glimpse on #10658 showed me, that it's
not the smallest of patches, but at least quite orthogonal to existing
code. So taking it in might at least not lead to regressions at
various places. The patch at #5048 is somewhat the other way around
--- rather small changes, but there might be a bit of code out there,
that calls x.parent() on elements of ArithmeticSubgroups, and *not*
expecting to always get back "SL2Z" as an answer. If not, then this
would be a reason to review this latter patch in a hurry --- but I
better sleep about it one or more nights, whether I like the change at
all (I think I do).


Cheers,
Georg