Comment on "exact solutions of the derivative nonlinear Schrödinger equation for a nonlinear transmission line".
In a recent article Kengne and Liu [Phys. Rev. E 73, 026603 (2006)] have presented a number of exact elliptic solutions for a derivative nonlinear Schrödinger equation. It is the aim of this Comment to point out that all these solutions given in Secs. II and III of this article (referred to as KL in the following) are subcases of the general solution of Eq. (KL.9). Conditions for the parameters A-E of the solutions given by Kengne and Liu can be found from general conditions for solitary and periodic elliptic solutions as shown in the following. Positive and bounded solutions can be found by considering the phase diagram. Therefore, the comment of Kengne and Liu that "we find its particular positive bounded solutions" can be specified.
Nickel
J
J
Department of Physics, University of Osnabrück, Barbarastrasse 7, D-49069 Osnabrück, Germany. jnickel@uos.de
Schürmann
H W
HW