An Exponential Stochastic Runge-Kutta Type Method of Order up to 1.5 for SPDEs of Nemytskii-type
Claudine von Hallern, Ricarda Mißfeldt, Andreas Rößler
TL;DR
This work develops ERKM1.5, a derivative-free exponential stochastic Runge-Kutta method for semilinear SPDEs with Nemytskii-type pointwise multiplicative noise. The scheme achieves strong temporal convergence of order up to $\gamma\in[1,\tfrac{3}{2})$ while keeping computational cost near linear in the problem dimension, contrasting with derivative-heavy Taylor-type methods. The authors provide a rigorous framework, a uniform $L^p$ moment bound, and a complete convergence proof, supported by spectral Galerkin implementation and numerical experiments including explicit, linear multiplicative, and nonlinear examples. The results demonstrate that ERKM1.5 offers a practical and efficient avenue for high-order SPDE simulations with reduced derivative evaluation burden and favorable scaling in dimensionality.
Abstract
For the approximation of solutions for stochastic partial differential equations, numerical methods that obtain a high order of convergence and at the same time involve reasonable computational cost are of particular interest. We therefore propose a new numerical method of exponential stochastic Runge-Kutta type that allows for convergence with a temporal order of up to 3/2 and that can be combined with several spatial discretizations. The developed family of derivative-free schemes is tailored to stochastic partial differential equations of Nemytskii-type, i.e., with pointwise multiplicative noise operators. We prove the strong convergence of these schemes in the root mean-square sense and present some numerical examples that reveal the theoretical results.
