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

• To: mathgroup at smc.vnet.net
• Subject: [mg124249] Re: how can one use mathematica get the approximate derivative of {x,y} data points?
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Sat, 14 Jan 2012 17:10:45 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```data = {#, Cos[#]} & /@ RandomReal[{0, 2 Pi}, 20];

f = Interpolation[data];

Plot[{f[x], f'[x]}, {x, Min[data[[All, 1]]], Max[data[[All, 1]]]}]

Bob Hanlon

On Sat, Jan 14, 2012 at 2:53 AM, Michael B. Heaney <mheaney at alum.mit.edu> 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
>

```

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