Re: how can one use mathematica get the approximate derivative of {x,y} data points?

*To*: mathgroup at smc.vnet.net*Subject*: [mg124241] Re: how can one use mathematica get the approximate derivative of {x,y} data points?*From*: Peter Breitfeld <phbrf at t-online.de>*Date*: Sat, 14 Jan 2012 17:07:59 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <jercda$19h$1@smc.vnet.net>

"Michael B. Heaney" wrote: > Hi, > > I have a set of {x,y} data points: > > {{0.03512, -0.5}, {0.0351181, -0.499}, ... {-0.113972, 0.699}, {-0.115072, > 0.7}} > > These data points look like a function y=f(x) when plotted on the x-y axes. > However, I do not know what the function f(x) is. But I need to get the > approximate derivative df/dx, as another set of data points. How can one > use Mathematica to do this? > > Thanks, > > Michael > > -- You can try Interpolation. fun[x_]:=x^2Cos[x] These will give approximate data for this function: data=Table[{x,fun[x]+RandomReal[{0,0.25}]},{x,0,1,0.5}] iF=Interpolation[data] Derivative: iF'[3] Plot[{iF[x],iF'[x]},{x,0,5}] -- _________________________________________________________________ Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de