Three applications for nonlinear least-chi^2 fitting of correlated data, optionally with Bayesian constraints.

QMBF/MBF - for fitting of Euclidean two-point and three-point functions in lattice field theory

XMBF - for simultaneous correlated fitting of multiple QMBF-type models, using global fit parameters

QMBCFN - for very general correlated fits, where each fit point (each degree of freedom) has its own arbitrary function.