建立关系用的。了解即可

多谢多谢

如果我没记错的话，copula function是用来练习边缘分布和联合分布之用的。没啥意思，指导即可。

能具体点吗

In probability theory and statistics, a copula is a kind of distribution function. Copulas are used to describe the dependence between random variables. They are named for their resemblance to grammatical copulas in linguistics.
The cumulative distribution function of a random vector can be written in terms of marginal distribution functions and a copula. The marginal distribution functions describe the marginal distribution of each component of the random vector and the copula describes the dependence structure between the components.
Copulas are popular in statistical applications as they allow one to easily model and estimate the distribution of random vectors by estimating marginals and copula separately. There are many parametric copula families available, which usually have parameters that control the strength of dependence. Some popular parametric copula models are outlined below.

sourc: http://en.wikipedia.org/wiki/Copula_(statistics)