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