h(copula, x, v, eps)copula object.x, v and return values close to 0 and 1 are
substituted by eps and 1 - eps, respectively. The default
eps value for most of the copulas is .Machine$double.eps^0.5.Schirmacher, D. and Schirmacher, E. (2008) Multivariate dependence modeling using pair-copulas. Enterprise Risk Management Symposium, Chicago.