Algorithm::lbfgs is an interface to liblbfgs, a c implementation of l-bfgs.

l-bfgs (limited-memory broyden-fletcher-goldfarb-shanno) is a quasi-newton method for unconstrained optimization. this method is especially efficient on problems involving a large number of variables.

generally, it solves a problem described as following:

min f(x), x = (x1, x2, ..., xn)