The problem consists of a stiff system of 4 non-linear ordinary differential equations. It represents a model for chemical pyrolysis studied by Datta in 1967 and describes a reaction involving six reactants. Although the problem was originally posed on the interval [0, 1e3], it is often integrated on a much longer interval because of the interesting properties of the solutions for large times ([0,1e13] has been used in the tests).
A complete description of the problem could be found in
e5.pdf
