  We introduce an ansatz of the PMNS matrix that consists of specific types of
transformations. Bi-maximal mixing is taken for the neutrino masses, while a
single-angle rotation in the 1-2 block is taken for the charged lepton masses.
Motivated by the implications of the recent results on neutrino oscillations,
$\theta_{23}$ in the first octant and non-zero $\theta_{13}$ are predicted by
the ansatz. Three physical mixing angles are expressed in terms of a single
variable, the 1-2 angle of charged leptons, so that a simple relation among the
angles has been obtained:
$\tan\theta_{13}=\sqrt{2}(\sin\theta_{23}-\sin\theta_{12})$. It follows that a
model of the inverted hierarchy that can produce the given ansatz is proposed.
