# RAD-TRAP, a program for the computation of the eigenvalues and eigenfunctions of the Holstein radiation-trapping equation

## Description

Abstract Radiation trapping is described by the Holstein equation, a Fredholm integral equation of the second kind. By combining analytical and numerical techniques, the presented code efficiently computes the eigenvalues and eigenfunctions of this equation for three important geometries: plane-parallel slab, long cylinder, and spherically symmetric geometry; all practically occuring spectral lineshapes are considered. The program is written in standard Fortran. Title of program: RAD-TRAP Catalogue Id: ACLB_v1_0 Nature of problem Computation of the eigenvalues and eigenfunctions of the Holstein integral equation describing radiation trapping in an atomic vapor (in one-dimensional geometries). Versions of this program held in the CPC repository in Mendeley Data ACLB_v2_0; RAD-TRAP 2; 10.1016/0010-4655(93)90009-2 ACLB_v1_0; RAD-TRAP; 10.1016/0010-4655(93)90108-O This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2019)