THE problem of ‘inverting’ singular matrices is by no means uncommon in statistical analysis. Rao 1 has shown in a lemma that a generalized inverse (g-inverse) always exists, although in the case of a ...
We show that, for an n × n random matrix A with independent uniformly anticoncentrated entries such that E ‖ A ‖ HS 2 ≤k n 2 , the smallest singular value σn(A) of A satisfies â„™{ σ n ( A )≤ ε n }≤Cε+2 ...
The estimated covariance matrix of the parameter estimates is computed as the inverse Hessian matrix, and for unconstrained problems it should be positive definite. If the final parameter estimates ...