On 4 October 2012 00:57, Maarten Derickx <m.derickx.stud...
> The reason is that q_expansion_basis returns power series and not modular
Yes, I know, but in practice one often wants to know if a given power
series is the q-expansion of an element of the space, and it seems
strange to me that you can do this by the ugly method of calling
"M(v)" and testing whether it raises an error, but you can't just use
"in". Maybe it's a matter of taste.