The following options can be set (here with default values):
stopval = -Inf, # stop minimization at this value xtol_rel =
1e-6, # stop on small optimization step maxeval = 1000, # stop on
this many function evaluations ftol_rel = 0.0, # stop on change
times function value ftol_abs = 0.0, # stop on small change of
function value check_derivatives = FALSE