If you look at the VI hierarchy, you will see that it uses the Power Spectrum.vi(s) which in turn use the Call Library Function node. The calculations are done in the DLL called by that node. If you look at the FFT.vi, you will see that they do the same thing for that VI.
They try to use highly optimized code for such calculations. If an improved algorithm becomes available, they can change the DLL and the LabVIEW code does not change.
Pressing the Theory button on the Generalized Fourier Spectrum VI will pop up a window with the formula used.
Lynn
