中文说明：提供inverse Wishart distribution 的pdf 即为probability density function，这个是matlab中不具备的，在统计中十分常用，参数是自变量x是一个p*p矩阵，和d,也是p*p矩阵，和自由度参数v
English Description：
Provides PDF is the probability density function of the inverse Wishart distribution, this is the MATLAB does not have, is commonly used in statistics, parameter is the variable x is a p*p matrix, and d, also p*p matrix, and the degrees of freedom parameter v