A Bose gas in an external potential is studied by means of the local d
ensity approximation. Analytical results are derived for the thermodyn
amic properties of an ideal Bose gas in a generic power-law trapping p
otential, and their dependence on the mutual interaction of atoms in t
he case of a non-ideal Bose gas. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.