This is documentation for an old release of SciPy (version 0.9.0). Read this page in the documentation of the latest stable release (version 1.15.1).
hilbert(x) -> y
Return Hilbert transform of a periodic sequence x.
If x_j and y_j are Fourier coefficients of periodic functions x and y, respectively, then
y_j = sqrt(-1)*sign(j) * x_j y_0 = 0
For even len(x), the Nyquist mode of x is taken zero.