  The (2+1)-dimensional generalized Nizhnik-Novikov-Veselov equations (GNNVEs)
are investigated in order to search the influence of initial solution to exact
solutions. The GNNVEs are converted into the combined equations of differently
two bilinear forms by means of the homogeneous balance of undetermined
coefficients method. Accordingly, the two class of exact N-soliton solutions
and three wave solutions are obtained respectively by using the Hirota direct
method combined with the simplified version of Hereman and the three wave
method. The proposed method is also a standard and computable method, which can
be generalized to deal with some nonlinear partial differential equations
(NLPDEs).
