A Novel Algorithm for the Numerical Integration of Systems of Ordinary Differential Equations Arising in Chemical Problems

Abstract

Simulation of large networks of chemical reactions via the numerical integration of large systems of ordinary differential equations is of growing importance in real-world problems. We propose an attractive novel numerical integration method, that is largely independent from ill-conditioning and is suitable for any nonlinear problem; moreover, the method, being exact for linear problems, is especially precise for quasi-linear problems, the most frequent kind in the real world. The method is based on a new approach to the computation of a matrix exponential, includes an automatic correction of rounding errors, is not too expensive computationally, and lends itself to a short and robust software implementation that can be easily inserted in large simulation packages. A preliminary numerical verification has been performed, with encouraging results, on two sample problems. The full source listing (in standard C language) of an academic version of the algorithm is freely available on request (e-mail address: Valerio.Parisi@roma2.infn.it), together with a very simple but very stiff chemical problem.