Derivatives of the noisy signal based on Gaussian wavelet

This code achieves n-th order derivatives of a noisy signal sampled at discrete time points.

Calculating noisy signal derivatives is a highly ill problem. According to the algorithm proposed in this paper (ref: https://doi.org/10.1016/j.chemolab.2003.08.001 ), a wavelet-based method can be used to suppress the noise, which is the basis of the code. The requirement for the input data is time vector is monotonic;