Observations on the tanh-coth expansion method for finding solutions to nonlinear evolution equations

The 'tanh-coth expansion method' for finding solitary travelling-wave solutions to nonlinear evolution equations has been used extensively in the literature. It is a natural extension to the basic tanh-function expansion method which was developed in the 1990s. It usually delivers three types of solution, namely a tanh-function expansion, a coth-function expansion, and a tanh-coth expansion. It is known that, for every tanh-function expansion solution, there is a corresponding coth-function expansion solution. It is shown that there is a tanh-coth expansion solution that is merely a disguised version of the coth solution. In many papers, such tanh-coth solutions are erroneously claimed to be 'new'. However, other tanh-coth solutions may be delivered that are genuinely new in the sense that they would not be delivered via the basic tanh-function method. Similar remarks apply to tan, cot and tan-cot expansion solutions

A Study about Finding Exact Solutions for Zeldovich Equation with Time-Dependent Coefficients by Using the Tanh Function Method

    In this work, we have been found explicit exact soliton wave solutions for Zeldovich equation with time-dependent coefficients, by using the tanh function method with nonlinear wave transform, in general case. The results obtained shows that these exact solutions are affected the nonlinear nature of the wave variable, it is also shown that this method is effective and appropriate for solving this kind of nonlinear PDEs, which are models of many applied problems in physics, chemistry and population evolution.

The (

The two variable (G'/G,1/G)-expansion method is employed to construct exact traveling wave solutions with parameters of two higher order nonlinear evolution equations, namely, the nonlinear Klein-Gordon equations and the nonlinear Pochhammer-Chree equations. When the parameters are replaced by special values, the well-known solitary wave solutions of these equations are rediscovered from the traveling waves. This method can be thought of as the generalization of well-known original (G'/G)-expansion method proposed by Wang et al. It is shown that the two variable (G'/G,1/G)-expansion method provides a more powerful mathematical tool for solving many other nonlinear PDEs in mathematical physics