Approximate the diagonal of the hessian by finite differences
The function is used to build a crude approximation to VCOV.
dMod_approxHessian(objfn, pars, h = 1e-04, diag = TRUE, ...)
dMod objective function
named parameter vector
stepsize of finite steps
compute only diagonal. Must be TRUE. The case diag = FALSE might be implemented in the future.
other arguments being passed to the objective function