how to obtain the variance covariance matrix cannot be applied how to get the variance matrix out of the hessian in hyperbolic distribution how to get matrix of hessian ________ function cannot be applied to the hessian? which function of vcov cannot be used which hessian cannot be used can you run the hessian function on sigma why does vcov function what is the vcov function which function can not be applied what is the function of vcov used for what is the hessian for delta can vcov be used to get the hessian of zeta what is vcov function cannot be used in vcov function what is the function vcov how to get variance from hessian function why does vcov not work at a sigma can vcov be used in hyperbolic equations