code: def fehalf(self):
          
          if self.__fehalf != None:
              return self.__fehalf
          self.log("fehalf")
          self.__fehalf = self.parcov.u * (self.parcov.s ** (0.5))
          self.log("fehalf")
          return self.__fehalf
docs: get the KL parcov scaling matrix attribute.  Create the attribute if
          it has not yet been created
  
          Returns
          -------
          fehalf : pyemu.Matrix