Algorithm 700: A Fortran software package for Sturm–Liouville problems

The package comprises two user-visible subprograms, sleign and zcount, and a set of special purpose subprograms invoked from them; the integration of the differential equations is done by the GERK software of Shampine and Watts [31 included with the package. zcount is used in the initial step for the semidefinite problem [1] to determine the translated index of the eigenvalue to be calculated by sleign.