Fig. 10
From: Quasi-differentiation and its applications to noisy time series data from complex systems
(a) The quasi-derivative of \(f(t) = \operatorname {sgn}(t+2.5) - \operatorname {sgn}(t-2.5)\) (graph shaded blue at \(w = 5\)) for window widths \(0.5 \le w \le 4.5\), in steps of \(\Delta w = 0.5\). (b) The heat map of quasi-derivative of \(f(t) = \operatorname {sgn}(t+2.5) - \operatorname {sgn}(t-2.5)\), with \(\Delta _w f(t)> 0\) being red, \(\Delta _w f(t) < 0\) being blue, and \(\Delta _w f(t) \approx 0\) being green.
