DAETK
A Differential-Algebraic Equation (DAE) is a coupled system of ordinary differential equations and algebraic constraint equations. The Differential Algebraic Equation Toolkit (DAETK) is a C++ library that implements some of the same algorithms as the Fortran code DASPK. It was an early attempt at developing object-oriented mathematical software in C++ and used PETSc to support distribured parallel computation.