34.1 Introduction

The RungeKutta unit in FLASH4 provides users with the tools to perform various kinds of (embedded) Runge Kutta (RK) iterations. The RK iterations are characterized by their implemented Butcher tableaus of various sizes and orders. The specific ODE to be solved must be transmitted via argument to the individual RK stepping routines. The RK routines contain no specifics of the ODE equations to be solved. This clean separation between the ODE function and the details of the RK iterations gives a universally applicable RK tool, which can be called from any FLASH4 application.