1. But

Return of result fields, in generalized coordinates or in the physical base, from the frequency to the temporal and vice versa, by fast Fourier transform (FFT).

This operator makes it possible, on the basis of a transitory evolution result on a generalized coordinate system or in the physical base, to obtain a frequency evolution result on the same basis by direct Fourier transformation of each of the transient evolution functions at each point and each component of the selected kinematic fields (displacements, speeds or accelerations). And conversely, from a result of frequency evolution on a generalized coordinate system or in the physical base, a result of transitory evolution is obtained on the same basis by inverse Fourier transformation of each of the harmonic evolution functions at each point and each component of the selected kinematic fields.

For each transformed evolution, the operation is analogous to that produced by calling the operator CALC_FONCTION [U4.32.04] with the keyword FFT.

The product concept is a concept such as:

· dyna_trans if the initial result transformed by FFT is of the dyna_harmo type,

· dyna_harmo if the initial result transformed by FFT is of the dyna_trans type,

· tran_gene if the initial result transformed by FFT is of type harm_gene,

· harm_gene if the initial result transformed by FFT is of type tran_gene.