Dressing by regularization to the Gerdjikov-Ivanov equation and the higher-order soliton

Higher-order solitons, as well as simple $N$-soliton solutions, of the Gerdjikov-Ivanov equation are derived by the dressing method based on the technique of regularization. By the dressing transformation for the eigenfunction associated with a seed solution, the regularity conditions of the dressed eigenfunctions are found to establish the relationship between the potential and the scattering data.