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Given a value and conditions, find a matrix with that value as its determinant

I'm not sure if the title is named too obscurely, so I'll give an example of what I'm talking.

Say we have an integer matrix: M= 0 a b 0 (sorry for weird formatting; cannot seem to write matrices properly on here - any help with that as well? :P )

I want to find all values $(a,b) \in (-2,-1,0,1,2)$ such that $det(M)=2$.

I've tried the following but I'm not sure how to finish it off / if this is the right way to go:

    import itertools
    for (a,b) in itertools.product([-2,-1,0,1,2], repeat=2):
          M = Matrix(ZZ, [[0,a],[b,0]])
    if M.determinant()==2:
         min_params = [(a,b)]
    print 'Sets of parameters with this determinant:', min_params

As I say, I feel like the start would be a good way to go, but I'm stuck when reaching elif, and I'm not sure if this is the right way to tackle this anyway!

Any help would be great!