Inverse Scattering Transform for the Derivative Nonlinear Schrodinger Equation

Since the Jost solutions of the derivative nonlinear Schrodinger equation do not tend to the free Jost solutions, when the spectral parameter tends to
infinity(|λ| → ∞), the usual inverse scattering transform (IST) must be revised. If we take the parameter k=λ^-1 as the basic parameter, the Jost solutions in
the limit of |k → ∞), do tend to the free Jost solutions, hence the usual procedure to construct the equations of IST in k-plane remains effective. After we derive the equation of IST in terms of k, we can obtain the equation of
IST in λ-plane by the simple change of parameters λ=kappa^-1. The procedure to derive the equation of IST is reasonable, and attention is never paid to the function W(x) introduced by the revisions of Kaup and Newell. Therefore, the
revision of Kaup and Newell can be avoided.