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In this paper some techniques for the dynamic analysis of non-classically damped linearsystems are reviewed and compared. All these methods are based on a transformation of the governingequations using a basis of complex or real vectors. Complex and real vector bases are presented andcompared. The complex vector basis is represented by the eigenvectors of the complex eigenproblemobtained considering the non-classical damping matrix of the system. The real vector basis is a set of Ritzvectors derived either as the undamped normal modes of vibration of the system, or by the loaddependent vector algorithm (Lanczos vectors). In this latter case the vector basis includes the staticcorrection concept. The rate of convergence of these bases, with reference to a parametric structuralsystem subjected to a fixed spatial distribution of forces, is evaluated. To this aim two error norms areconsidered, the first based on the spatial distribution of the load and the second on the shear force at thebase due to impulsive loading. It is shown that both error norms point out that the rate of convergence isstrongly influenced by the spatial distribution of the applied forces.