Positive definite matrix entries in Maple?

[GaryG]

I've just started using Maple and I'm trying to solve an equation involving
matrices using isolve to solve for the entries in the matrix. At the moment
I have: isolve(convert(U+U^2-S, set)) (where the entries of U are unknown) I
would like to specify somehow that all the entries in the matrix U must be
positive. How do I do this without writing out explicity m_1,1 > 0, etc. for
every entry? Thanks.