  We present an autonomous phase-plane describing the evolution of field
equations containing an agegraphic dark energy in 5D Brans- Dicke cosmology. To
observationally verify the numerical results, we simultaneously solve the
equations by constraining the model parameters with SNe Ia data. We find
conditions for the existence and stability of the critical points (states of
the universe) and numerically examine the cosmological parameters. We also
investigate the model by means of statefinder diagnostic.
