scipy.fftpack.cs_diff

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

cs_diff(x, a, b, period=2*pi) -> y

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

Input:

a,b

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

period

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

Notes:

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