Abstract:
In evolution equations for a complex amplitude, the equation for the phase is much more intricate than for the amplitude. Nevertheless, general methods should be applicable to both variables. In the example of the traveling-wave reduction of the complex cubic–quintic Ginzburg–Landau (CGL5) equation, we explain how to overcome the difficulties arising in two methods: (1) the criterion that the sum of residues of an elliptic solution is zero and (2) the construction of a first-order differential equation admitting a given equation as a differential consequence (subequation method).