On numerical methods to second-order singular initial value problems with additive white noise

In this work, we investigate the strong convergence of the Euler-Maruyama method for second-order stochastic singular initial value problems with additive white noise. The singularity at the origin brings a big challenge that the classical framework for stochastic differential equations and numerical schemes cannot work. By converting the problem to a first-order stochastic singular differential system, the existence and uniqueness of the exact solution is studied. Moreover, under some suitable assumptions, it is proved that the Euler-Maruyama method is of (1/2 - epsilon) order convergence in mean-square sense, where epsilon is an arbitrarily small positive number, which is different from the consensus that the Euler-Maruyama method is convergent with first order in strong sense when solving stochastic differential equations with additive white noise. While, it is found that if the diffusion coefficient vanishes at the origin, the convergence order in mean-square sense will be increased to 1 - epsilon. Our theoretical findings are well verified by numerical examples. (C) 2022 Elsevier B.V. All rights reserved.