# scipy.fftpack.sc_diff

scipy.fftpack.sc_diff(x, a, b, period=None, _cache={})

  Return (a,b)-sinh/cosh pseudo-derivative 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)*sinh(j*a*2*pi/period)/cosh(j*b*2*pi/period) * x_j
      y_0 = 0

  Parameters:
    x array_like

      Input array.

    a,b float

      Defines the parameters of the sinh/cosh pseudo-differential operator.

    period float, optional

      The period of the sequence x. Default is 2*pi.

  Notes

  `sc_diff(cs_diff(x,a,b),b,a) == x` For even `len(x)`, the Nyquist mode of x is taken as zero.