scipy.fftpack.cs_diff¶
- scipy.fftpack.cs_diff(x, a, b, period=None, _cache={})[source]¶
Return (a,b)-cosh/sinh pseudo-derivative of a periodic sequence.
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
Parameters: x : array_like
The array to take the pseudo-derivative from.
a, b : float
Defines the parameters of the cosh/sinh pseudo-differential operator.
period : float, optional
The period of the sequence. Default period is 2*pi.
Returns: cs_diff : ndarray
Pseudo-derivative of periodic sequence x.
Notes
For even len(x), the Nyquist mode of x is taken as zero.