IMEX-RK finite volume methods for nonlinear 1d parabolic PDEs. Application to option pricing
J. G. López-Salas, M. Suárez-Taboada, M. J. Castro, A. M. Ferreiro-Ferreiro, J. A. García-Rodríguez
TL;DR
This paper develops a 2nd-order implicit-explicit Runge-Kutta finite-volume framework for solving nonlinear 1D parabolic PDEs in option pricing. By discretizing convection and source terms explicitly and diffusion implicitly, the scheme achieves high accuracy on non-smooth initial data and avoids fixed-point iterations, while maintaining computational efficiency. The authors demonstrate strong convergence and substantial time-step speedups over explicit methods on both linear barrier-options and nonlinear counterparty-risk models, with accurate Greeks. The approach provides a robust, extendable tool for efficient pricing and risk assessment in financial contexts with nonlinear PDEs.
Abstract
The goal of this paper is to develop 2nd order Implicit-Explicit Runge-Kutta (IMEX-RK) finite volume (FV) schemes for solving 1d parabolic PDEs for option pricing, with possible nonlinearities in the source and advection terms. The spatial semi-discretization of the advection is carried out by combining finite volume methods with 2nd order state reconstructions; while the diffusive terms are discretized using second-order finite differences. The time integration is performed by means of IMEX-RK time integrators: the advection is treated explicitly, and the diffusion, implicitly. The obtained numerical schemes have several advantages: they are computationally very efficient, thanks to the implicit discretization of the diffusion in the IMEX-RK time integrators, which allows to overcome the strict time step restriction; they yield second-order accuracy for even nonlinear problems and with non-regular initial conditions; and they can be extended to higher order.
