The Helmholtz equation is considered. The matrices decomposition algorithms for Legendre spectral collocation approximation, which nearly reduce a half of scale for original discrete system, are achieved by the centrosymmetry and positivity. Also, the di erence and finite element preconditioning...

This thesis consists of two parts. The first part contributes statistical methodology for nonnegative integer-valued time series. The second part of this thesis consists of two chapters. One chapter is concerned with the development of efficient estimators of the marginal distribution functions...