1. A method for performing dynamic analysis of a physical system, the method comprising obtaining a physical system or a design of a physical system; translating said physical system or design of a physical system into a mathematical model by causing a computer system programmed to carry out such translation to perform steps of: sub-structuring said system into a plurality of sub-structures; modelling said sub-structures into sub-structure models and modelling interfaces between said sub-structure models; combining said sub-structure models at the interfaces into a combined system; solving the combined system, wherein said modelling comprises performing a generalized eigenvector analysis on a discretised model of at least a subassembly including at least two said sub-structures; said computer system presenting results of the translation to a user, to enable such user to determine dynamic properties of said physical system or said design of a physical system.