The right hand sides of the equations depend in addition on an independent variable, e.g. a concentration .
Special applications are receptor-ligand binding models based on the mass equilibrium equation.
Gradients are evaluated analytically in a numerically stable way based on the implicit function theorem. An additional main program takes over some organizational ballast and reads in all problem data. A user provided subroutine is required to evaluate the system of equations, the fitting criterion and corresponding gradients. Special binding models with up to ten ligands and receptors are implemented in addition.