Return inverse 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)*tanh(j*h*2*pi/period) * x_j y_0 = 0
For more details, see tilbert.
scipy.fftpack.tilbert
scipy.fftpack.hilbert