code: def freqEigvalRatio(self,isotropic=False):
          
          if isotropic:
              sortedEig= sorted(numpy.fabs(self._dOdJpEig[0]))
              return sortedEig[2]/sortedEig[1]
          else:
              return numpy.sqrt(self._sortedSigOEig)[2]\
                  /numpy.sqrt(self._sortedSigOEig)[1]
docs: NAME:
  
             freqEigvalRatio
  
          PURPOSE:
  
             calculate the ratio between the largest and 2nd-to-largest (in abs)
             eigenvalue of sqrt(dO/dJ^T V_J dO/dJ) 
             (if this is big, a 1D stream will form)
  
          INPUT:
  
             isotropic= (False), if True, return the ratio assuming an isotropic action distribution (i.e., just of dO/dJ)
  
          OUTPUT:
  
             ratio between eigenvalues of fabs(dO / dJ)
  
          HISTORY:
  
             2013-12-05 - Written - Bovy (IAS)