Cobimaximal Mixing with Dirac Neutrinos

If neutrinos are Dirac, the conditions for cobimaximal mixing, i.e. $theta_{23}=pi/4$ and $delta_{CP}=pm pi/2$ in the $3 times 3$ neutrino mixing matrix, are derived. One example with $A_4$ symmetry and radiative Dirac neutrino masses is presented.