def _getActorLimits(self):
        """ Returns a list of 2-tuples, e.g. [(-3.14, 3.14), (-0.001, 0.001)],
            one tuple per parameter, giving min and max for that parameter.
        """
        actorLimits = []

        for _ in range(self.env.numOffbids):
            for _ in self.env.generators:
                actorLimits.append((0.0, self.env.maxMarkup))

        for _ in range(self.env.numOffbids):
            for _ in self.env.generators:
                if self.env.maxWithhold is not None:
                    actorLimits.append((0.0, self.env.maxWithhold))

        logger.debug("Actor limits: %s" % actorLimits)

        return actorLimits