GETFEM is a library allowing the computation of any elementary matrix (even for mixed finite element methods) on the largest class of methods and elements, and for arbitrary dimension.

Qalculate! is small and simple to use but with much power and versatility underneath. Features include customizable functions, units, arbitrary precision, plotting, and a graphical interface that uses a one-line fault-tolerant expression entry (although it supports optional traditional buttons).

GeoIP is a C library that enables the user to find the country that any IP address or hostname originates from. It uses a file based database.

gElemental is a GTK+ periodic table viewer that provides detailed information about chemical elements.

Polymake started out as a tool for the algorithmic treatment of convex polyhedra. By now it also deals with finite simplicial complexes, tight spans of finite metric spaces, polyhedral surfaces, and other discrete mathematical objects.

The libelf1t64 package provides a shared library which allows reading and writing ELF files on a high level. Third party programs depend on this package to read internals of ELF files. The programs of the elfutils package use it also to generate new ELF files.