def expQt(self, t):
eLambdaT = np.diag(self._exp_lt(t)) <EOL>Qs = self.v.dot(eLambdaT.dot(self.v_inv))   <EOL>return np.maximum(<NUM_LIT:0>,Qs)<EOL>
Parameters
----------

 t : float
    Time to propagate

Returns
--------

 expQt : numpy.array
    Matrix exponential of exo(Qt)