A further improved extended Fan sub-equation method and its application to the (3+1)-dimensional Kadomstev-Petviashvili equation

A further improved extended Fan sub-equation method is proposed to seek more types of exact solutions of non-linear partial differential equations. Applying this method to the (3+1)-dimensional Kadomstev-Petviashvili equation, we obtain many new and more general non-travelling wave solutions including soliton-like solutions, triangular-like solutions, single and combined non-degenerate Jacobi elliptic wave function-like solutions, Weierstrass elliptic doubly-like periodic solutions.