enforce bounds violation resulting from the
        parameter pertubation calculations

def enforce_bounds(self):
        """ enforce bounds violation resulting from the
        parameter pertubation calculations

        """
        too_big = self.parameter_data.loc[:,"parval1"] > \
            self.parameter_data.loc[:,"parubnd"]
        self.parameter_data.loc[too_big,"parval1"] = \
            self.parameter_data.loc[too_big,"parubnd"]

        too_small = self.parameter_data.loc[:,"parval1"] < \
            self.parameter_data.loc[:,"parlbnd"]
        self.parameter_data.loc[too_small,"parval1"] = \
            self.parameter_data.loc[too_small,"parlbnd"]