Check if is in span

[AmanieOxana]

Given a matrix, check whether it is in the span of a certain set of matrices. Implement in_span inside src/paulie/application with tests found in the folder tests.

[Newtech66]

By span, does that mean a linear combination or a sequence of nested commutators?

[AmanieOxana]

span means the real linear combinations

[Newtech66]

Well, so it is equivalent to solving a set of linear equations in $n\times m$ variables, right?

$$ \sum_{i} a_i T^{i}_{jk} = V_{jk} $$