The differential cross-sections are integrated and sampled using the CERNLIB package DIVON4 [5]. The package consists of a collection of routines to aid in the numerical integration of functions of several variables and to sample points in a multi-dimensional coordinate space from a specified probability density function. The algorithm adaptively partitions a multi-dimensional coordinate space into a set of axis-oriented hyper-rectangular regions, based on a user provided function. These regions are then used for a stratified sampling estimate of the integral of the function, or to sample random vectors from the coordinate space with probability density that of the function.
The integration and importance sampling are extremely fast in LQ2\ since the cross-section is a function of a single variable.