  A specific scale factor in Robertson-Walker metric with the prospect of
giving the overall cosmic history in a unified picture roughly is considered.
The corresponding energy-momentum tensor is identified as that of two scalar
fields where one plays the roles of both inflaton and dark matter while the
other accounts for dark energy. A preliminary phenomenological analysis gives
an order of magnitude agreement with observational data. The resulting picture
may be considered as a first step towards a single model for all epochs of
cosmic evolution.
