Re: plotting the derivative of a splined/interpolated function

*To*: mathgroup at smc.vnet.net*Subject*: [mg50758] Re: [mg50682] plotting the derivative of a splined/interpolated function*From*: "David Annetts" <davidannetts at ihug.com.au>*Date*: Sun, 19 Sep 2004 21:39:14 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi Todd, > BUT I can't seem to plot either dervie or dervie2 with the standard > Plot ParametricPlot commands > > So the question becomes is, how to I plot the derrivative of an > interpolated or slpined function? data = Table[{t, Sin[2 Pi t / 128]}, {t, 0, 128, .5}]; dint = Interpolation[data]; Plot[{dint[t], dint'[t]}, {t, 0, 128}, PlotStyle -> {Red, Black}]; Plot[{dint[t], dint''[t]}, {t, 0, 128}, PlotStyle -> {Red, Black}]; Works fine for me. With regard to differentiating splines, I'd suggest interpolating the spline, then differentiating the interpolant as above. Regards, Dave.