An Improved F-Expansion Method and Its Application to Coupled Drinfel'd-Sokolov-Wilson Equation

With the aid of computerized symbolic computation, an improved F-expansion method is presented to uniformly construct more new exact doubly periodic solutions in terms of rational formal Jacobi elliptic function of nonlinear partial differential equations (NPDEs). The coupledDrinfel'd-Sokolov-Wilson equation is chosen to illustrate the method. As aresult, we can successfully obtain abundant new doubly periodicsolutions without calculating various Jacobi elliptic functions. Inthe limit cases, the rational solitary wave solutions and trigonometric function solutions are obtained as well.