Formula 1
Formula 2
Formula 3
The finite Fourier transform always exists for well defined .
Formula 4
Formula 5
defined for - , the inverse Fourier transform of X(f) is defined as a real valued function of time,
Formula 6
System superposition:
Formula 7
Formula 8
For an ensemble {xi(t): } of N time history
Formula 9
records with a mean, , and a standard deviation, , , where the mean is estimated by
Formula 10
varying envelope that begins at zero and ends at zero over a certain period of time, .
Formula 11
Formula 12
for some and where .
Formula 13
For an ensemble of N time history records with