  We find a matter-wave solution of Bose-Einstein condensates trapped in a
harmonic-oscillator potential and subjected to a homogeneous gravitational
field, by means of the extended tanhfunction method. This solution has as
special cases the bright and dark solitons. We investigate the dynamics and the
kinematics of these solutions, and the role of gravity is sketched. It is shown
that these solutions can be generated and manipulated by controlling the s-wave
scattering length, without changing the strengths of the magnetic and
gravitational fields.
