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# scipy.fftpack.hilbert

`scipy.fftpack.``hilbert`(x, _cache={})

  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

  Notes:
    If sum(x,axis=0)==0 then
      hilbert(ihilbert(x)) == x

    For even len(x), the Nyquist mode of x is taken zero.

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