I have a symmetric matrix whose elements are given by
$$A_{wx} = \sum_{i=1}^{N} {^{wx}\lambda}_i^{2}$$
where ${^{wx}\lambda}_i = {^{xw}\lambda}_i \ge 0$, and ${^{ww}\lambda}_i = 1 \ \forall w,i$.
I might be asking something really trivial here, but is it possible to prove that $\boldsymbol{A}$ is positive semidefinite, or to find conditions for $\boldsymbol{A}$ to be positive semidefinite?
Thanks.