## Q. Harmonic Analysis of a Radiating Elastic Structure (HAR4)

Using the operator [G] described in the preceding paragraph,the system of equations can be written:

The user must specify the excitation frequency and definethe prescribed excitations and/or loads located on the nodes (see section III.D, EXCITATIONS and LOADS entries). Thecode computes the real and imaginary parts of the displacement and pressurefields. It is possible to restart with new excitation frequencies without theneed for a new assembly phase. In this case, the number of cases of loadingmust remain unchanged, but the number of computation frequencies can be smallerthan the initial number of frequencies (see Section III.D, FREQUENCY and NLOAD entries).

After symmetrization, the system can be written:

The matrices are assembled and stored in a file by columns. Gaussian algorithms are used to solve the problem, in single or doubleprecision. The internal losses of materials can be taken into account. Theinformation about the damping elements, the conditions on the boundary, thenear field and the far field, presented in HAR3, stillapply.