def param_array(self):
        """
        Array representing the parameters of this class.
        There is only one copy of all parameters in memory, two during optimization.

        !WARNING!: setting the parameter array MUST always be done in memory:
        m.param_array[:] = m_copy.param_array
        """
        if (self.__dict__.get('_param_array_', None) is None) or (self._param_array_.size != self.size):
            self._param_array_ = np.empty(self.size, dtype=np.float64)
        return self._param_array_
Array representing the parameters of this class.
        There is only one copy of all parameters in memory, two during optimization.

        !WARNING!: setting the parameter array MUST always be done in memory:
        m.param_array[:] = m_copy.param_array