TY - JOUR TI - On Galerkin Approximations for the Zakai Equation with Diffusive and Point Process Observations AB - This paper studies Galerkin approximations applied to the Zakai equation of stochastic filtering. The basic idea of this approach is to project the infinite-dimensional Zakai equation onto some finite-dimensional subspace generated by smooth basis functions; this leads to a finite-dimensional system of stochastic differential equations that can be solved numerically. The contribution of the paper is twofold. On the theoretical side, existing convergence results are extended to filtering models with observations of point-process or mixed type. On the applied side, various issues related to the numerical implementation of the method are considered; in particular, we propose working with a subspace that is constructed from a basis of Hermite polynomials. The paper closes with a numerical case study. SP - 2036 EP - 2062 UR - http://epubs.siam.org/doi/abs/10.1137/110837395 PY - 2013-10-01 JO - SIAM Journal on Numerical Analysis (Society for Industrial and Applied Mathematics) AU - Frey, RĂ¼diger AU - Schmidt, Thorsten AU - Xu, Ling ER -