cs_diff — SciPy v1.15.3 Manual (original) (raw)

scipy.fftpack.

scipy.fftpack.cs_diff(x, a, b, period=None, _cache=<_thread._local object>)[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(ja2pi/period)/sinh(jb2*pi/period) * x_j y_0 = 0

Parameters:

xarray_like

The array to take the pseudo-derivative from.

a, bfloat

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

periodfloat, optional

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

Returns:

cs_diffndarray

Pseudo-derivative of periodic sequence x.

Notes

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