zgges(3) on Linux
The text 7f61f00e7eb5, as Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
compute for a pair of N-by-N complex nonsymmetric matrices (A,B), the generalized eigenvalues, the generalized complex Schur form (S, T), and optionally left and/or right Schur vectors (VSL and VSR)