he ANALYS module computes the problem solution for the required frequency steps. Files 1, 3 and 4 are always required as input. For external load cases File 9, and for incoherence analysis Files 7 and 11 are also required as input.

ANALYS performs the following computational steps:

1. Forms the flexibility matrix for the discretized model.
2. Computes the impedance matrix for the discretized model.
3. Determines the external load or seismic load vectors, including incoherency effects
4. Solves the equation system for each frequency step, using triangularization and back-substitution algorithms and obtains transfer functions for each degree of freedom.

The solution output computed by the ANALYS module contains the transfer functions which depending on the option required are from the control motion to the final motions or from external loads to total displacements. In either case, the results are stored in File 8. File5 and File 6 are unformatted restart files.

Interpolation of transfer functions in frequency domain and further output requirements are handled by the modules described below.