Fig.3
From: Quasi-differentiation and its applications to noisy time series data from complex systems
(a) The pair of time windows \((t-w,t)\) (blue shaded regions) and \((t,t+w)\) (green shaded regions), shown at different values of t for \(w=1\), superimposed on \(f(t)=\tanh (t)\) (red). (b) The function \(f(t) = \tanh (t)\) (red) and its derivative \(f'(t) = \operatorname {sech}^2(t)\) (green), and its quasi-derivative \(\Delta _w f(t)\) (blue) obtained using a pair of sliding windows with width \(w=1\).
