A Matlab package for automatically generating Runge-Kutta trees, order conditions, and truncation error coefficients

Abstract

In designing parts of Runge-Kutta methods, order conditions and truncation error coefficients (TECs) are needed. Order conditions and TECs are typically presented as a set of trees combined with rules for producing algebraic expressions from the trees. The tree sets are defined recursively and can be generated by hand only for low orders. This article describes a package of Matlab routines for automatically generating Runge-Kutta trees, order conditions, and TECs. The routines are capable of generating Maple code, Matlab code, or LaTeX expressions for ODEs or DAEs of index 1 and 2. In producing the package, two theoretical problems are tackled: (a) avoiding the repeated generation of the same tree and (b) the efficient storage of TECs.