'Sets size thresholds for scientific notation.
``lims`` is a two-element sequence containing the powers of 10
that determine the switchover threshold. Numbers below
``10**lims[0]`` and above ``10**lims[1]`` will be displayed in
scientific notation.
For example, ``formatter.set_powerlimits((-3, 4))`` sets the
pre-2007 default in which scientific notation is used for
numbers less than 1e-3 or greater than 1e4.
.. seealso:: Method :meth:`set_scientific`'

def set_powerlimits(self, lims):

    if (len(lims) != 2):
        raise ValueError(u"'lims'    must    be    a    sequence    of    length    2")
    self._powerlimits = lims
