class_docstr: Class that defines linalg operation on an array
  
  simplest version as benchmark
  
  linear algebra recipes for multivariate normal and linear
  regression calculations
code: def meigh(self):
      evals, evecs = linalg.eigh(self.m)
      sortind = np.argsort(evals)[::-1]
      return evals[sortind], evecs[:, sortind]
  
imports: import numpy
  from scipy import linalg
  from statsmodels.tools.decorators import cache_readonly
label_desc: Use image node_id 13 for calling the PlainMatrixArray obj's underlying member method code with example usage: obj.meigh() and returns: evals,  evecs