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# scipy.fftpack.tilbert

`scipy.fftpack.``tilbert`(x, h, period=None, _cache={})

  Return h-Tilbert 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)*coth(j*h*2*pi/period) * x_j
      y_0 = 0

  Parameters : | x : array_like The input array to transform. h : float Defines the parameter of the Tilbert transform. period : float, optional The assumed period of the sequence. Default period is `2*pi`.
  Returns : | tilbert : ndarray The result of the transform.

  Notes

  If `sum(x, axis=0) == 0` and `n = len(x)` is odd then `tilbert(itilbert(x)) == x`.

  If `2 * pi * h / period` is approximately 10 or larger, then numerically `tilbert == hilbert` (theoretically oo-Tilbert == Hilbert).

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

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