class_docstr: Base Class for multivariate elliptical distributions, normal and t
  
  contains common initialization, and some common methods
  subclass needs to implement at least rvs and logpdf methods
class_docstr_tok: ["Base","Class","for","multivariate","elliptical","distributions",",","normal","and","t","contains","common","initialization",",","and","some","common","methods","subclass","needs","to","implement","at","least","rvs","and","logpdf","methods"]
docstr: standard deviation, square root of diagonal elements of sigma
          
code: def std_sigma(self):
      """standard deviation, square root of diagonal elements of sigma"""
      return np.sqrt(np.diag(self.sigma))
  
imports: import numpy
  from scipy import special
  from statsmodels.sandbox.distributions.multivariate import mvstdtprob
  from .extras import mvnormcdf
label_desc: Use image node_id 14 for calling the MVElliptical obj's underlying member method code with example usage: obj.std_sigma() and returns: np