The numerical Range of Matrix Polynomials
Suppose that is a real symmetric matrix of order . Denote by the nullity of . For a nonempty subset of , let be the principal submatrix of obtained from by deleting the rows and columns indexed by . When , we call a P-set of . It is known that every P-set of contains at most elements. The graphs of even order for which one can find a matrix attaining this bound are now completely characterized. However, the odd case turned out to be more difficult to tackle. As a first step...
The reciprocal super Catalan matrix has entries [...] . Explicit formulæ for its LU-decomposition, the LU-decomposition of its inverse, and some related matrices are obtained. For all results, q-analogues are also presented.