Following up on issue 1:

On Saturday, July 2, 2016 at 9:42:53 PM UTC-7, Rob Harron wrote:
>
> sage: chi = kronecker_character(3*34603)
> sage: M = ModularSymbols(chi, 2, sign=1, base_ring=GF(3))
> ...
> File 
> "/projects/sage/sage-6.10/local/lib/python2.7/site-packages/sage/modular/modsym/relation_matrix.py",
>  
> line 126, in modS_relations
>     assert j != -1
> AssertionError
>
>
Inspecting the traceback suggests that the issue is here:

sage: chi = kronecker_character(3*34603)
sage: from sage.modular.modsym.manin_symbol_list import 
ManinSymbolList_character
sage: m = ManinSymbolList_character(chi,2); m

Manin Symbol List of weight 2 for Gamma1(103809) with character [-1, -1]

sage: for i in range(len(m)):
sage:    j, s = m.apply_S(i)
sage:    if not j != -1: print i, j, s #should print nothing

34604 -1 0
69207 -1 0
126878 -1 0


That value of j appears to be the index of some tuple in the underlying list of 
m; an index of -1 means "not found". This suggests that the list of Manin 
symbols is not being generated correctly for some reason.


That generation happens in the file src/sage/modular/modsym/p1list.pyx. Here is 
a test that seems to isolate the issue:


sage: import sage.modular.modsym.p1list as p1list
sage: for (i,j) in p1list.P1List(103809):
sage:    if i != 1 and i != 3: print (i,j)

(0, 1) #should also return (34603, 1) and (34603, 2). 


There seems to be a cutover above level 46340, which might be exposing some 
poorly tested legacy code.


I'm not sure whether the other issue is related, but it does appear to be in 
the same file, so I wouldn't rule it out. 


Kiran



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