Calculate the time derivation of a signal
"Derive" computes the time derivative of
the given signal with respect to the x-axis scaling. Internally, an
antisymmetric FIR filter is used to
perform the discrete differentiation.
- differentiation step d (as number of samples),
which is the length of the FIR filter (one-sided excluding zero)
used for the estimation of the local differential quotient.
y = Derive(x,d);
Parks/Burrus , Oppenheim/Schafer