Analysis of Possible Evolution of Dark Energy by Using a Power Series

We simulate the density of dark energy by using a power series to analyse the possible evolution of dark energy. The parameters are constrained from the newly released Gold sample of the supernova dataset. The evolutions of dark energy, as the power series from two free parameters to five free parameters, have the common and the different characters. We may conclude that either the density of dark energy possibly oscillates or increases after
it decreases to a minimum value. Accordingly, the state equation of dark energy oscillates or evolves from ω_de>-1 in the past to ω_de<-1 around the present epoch.