Kernel Based Quadrature on Spheres and Other Homogeneous Spaces

Quadrature formulas for spheres, the rotation group, and other compact, homogeneous manifolds are important in a number of applications and have been the subject of recent research. The main purpose of this paper is to study coordinate independent quadrature (or cubature) formulas associated with certain classes of positive definite and conditionally positive definite kernels that are invariant under the group action of the homogeneous manifold. In particular, we show that these formulas are accurate—optimally so in many cases—and stable under an increasing number of nodes and in the presence of noise, provided the set X of quadrature nodes is quasi-uniform. The stability results are new in all cases. In addition, we may use these quadrature formulas to obtain similar formulas for manifolds diffeomorphic to Sn, oblate spheroids for instance. The weights are obtained by solving a single linear system. For S2, and the restricted thin plate spline kernel r2log r, these weights can be computed for two-thirds of a million nodes, using a preconditioned iterative technique introduced by us

Radial Basis Function Based Quadrature over Smooth Surfaces

The numerical approximation of denite integrals, or quadrature, often involves the construction of an interpolant of the integrand and subsequent integration of the interpolant. It is natural to rely on polynomial interpolants in the case ofone dimension; however, extension of integration of polynomial interpolants to two or more dimensions can be costly andunstable. A method for computing surface integrals on the sphere is detailed in the literature (Reeger and Fornberg,Studies in Applied Mathematics, 2016). The method uses local radial basis function (RBF) interpolation to reducecomputational complexity when generating quadrature weights for the particular node set. This thesis expands upon thesame spherical quadrature method and applies it to an arbitrary smooth closed surface dened by a set of quadraturenodes and triangulation

Meshfree Methods Using Localized Kernel Bases

Radial basis functions have been used to construct meshfree numerical methods for interpolation and for solving partial differential equations. Recently, a localized basis of radial basis functions has been developed on the sphere. In this dissertation, we investigate applying localized kernel bases for interpolation, approximation, and for novel discretization methods for numerically solving partial differential equations and integral equations. We investigate methods for partial differential equations on spheres using newly explored bases constructed from radial basis functions and associated quadrature methods. We explore applications of radial basis functions to anisotropic nonlocal diffusion problems and we develop theoretical frameworks for these methods