scipy.fftpack.
diff#
- scipy.fftpack.diff(x, order=1, period=None, _cache=<_thread._local object>)[source]#
- Return kth derivative (or integral) of a periodic sequence x. - If x_j and y_j are Fourier coefficients of periodic functions x and y, respectively, then: - y_j = pow(sqrt(-1)*j*2*pi/period, order) * x_j y_0 = 0 if order is not 0. - Parameters:
- xarray_like
- Input array. 
- orderint, optional
- The order of differentiation. Default order is 1. If order is negative, then integration is carried out under the assumption that - x_0 == 0.
- periodfloat, optional
- The assumed period of the sequence. Default is - 2*pi.
 
 - Notes - If - sum(x, axis=0) = 0then- diff(diff(x, k), -k) == x(within numerical accuracy).- For odd order and even - len(x), the Nyquist mode is taken zero.