ASKSAGE: Sage Q&A Forum - Latest question feedhttps://ask.sagemath.org/questions/Q&A Forum for SageenCopyright Sage, 2010. Some rights reserved under creative commons license.Sat, 05 Jan 2013 04:24:24 -0600Plotting fundamental domains of modular subgroups from generators and cusp widthshttps://ask.sagemath.org/question/9283/plotting-fundamental-domains-of-modular-subgroups-from-generators-and-cusp-widths/I have a number of genus zero, index 24 modular subgroups (some congruence, some not). For each of these subgroups, I have the cusp widths, and a set of generators as explicit 2x2 matrices. How can I use these to plot the fundamental domain for each group? I suspect a lot of this material is in the *KFarey* package, but I'm having trouble putting it all together.
Thanks!JimereeSat, 01 Sep 2012 01:36:43 -0500https://ask.sagemath.org/question/9283/Check whether a modular subgroup is congruence from its generatorshttps://ask.sagemath.org/question/9691/check-whether-a-modular-subgroup-is-congruence-from-its-generators/I want to input the generators of a specific subgroup of the modular group $\Gamma = PSL(2,\mathbb{Z})$ as explicit $2\times 2$ matrices, and have Sage tell me whether that subgroup is congruence. Clearly I need to use the command `is_congruence()` for the second part, but I'm having trouble inputting the subgroup generators. Potentially it is something very simple - can anyone help? Thanks.JimereeSat, 05 Jan 2013 04:24:24 -0600https://ask.sagemath.org/question/9691/Permutation Representations and the Modular Grouphttps://ask.sagemath.org/question/9202/permutation-representations-and-the-modular-group/Hi!
Given a congruence subgroup of the modular group G = SL2Z, how can one use Sage to find the permutation representations of G on the cosets of each of those normal subgroups? Specifically I am looking at the subgroups on page 22 here: http://arxiv.org/pdf/1201.3633v2.pdf
Many thanks!
JimereeFri, 03 Aug 2012 04:19:42 -0500https://ask.sagemath.org/question/9202/