Re: Reconstructing data points from a InterpolatingFunction object

• To: mathgroup at smc.vnet.net
• Subject: [mg66489] Re: [mg66483] Reconstructing data points from a InterpolatingFunction object
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Wed, 17 May 2006 03:29:15 -0400 (EDT)
• References: <200605160349.XAA01097@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```On 16 May 2006, at 12:49, Eckhard Schlemm wrote:

> Hello everyone,
>
> My question is probably rather simple to answer but I just don't
> know how to
> do it.
>
> I am nummerically solving a differential equation using NDSolve and
> then I
> want to apply a NonlinearFit on the resulting InterpolatingFunction
> which NDSolve
> created and from which the InterpolatingFunction is created....Is
> there any
> fast and direct way to get these data points ? (There must be....)
>
>
> Eckhard
>
>

Indeed, the data points can be got out from any
InterpolatingFunction, but the most direct method to do so depends on
which version of Mathematica you are using. You can see it on an
example. I Mathematica 5.1:

ls = {{0, .1}, {1, .2}, {2, .3}, {3, .4}};
f = Interpolation[ls, InterpolationOrder -> 1];
f//InputForm
InterpolatingFunction[{{0., 3.}}, {2, 0, True, Real, {1},
{0}}, {{0., 1., 2., 3.}}, {{0, 1, 2, 3, 4},
{0.1, 0.2, 0.3, 0.4}}, {Automatic}]

f[[-2]]

{{0,1,2,3,4},{0.1,0.2,0.3,0.4}}

On the other hand in Mathematica 4.1 the same code returns

InterpolatingFunction[{{0., 3.}}, {1, 0, True, Real, {1},
{0}}, {{0., 1., 2., 3.}}, {{0, 1, 2, 3, 4},
{0.1, 0.2, 0.3, 0.4}}]

So you can get the data with f[[-1]].

Andrzej Kozlowski

```

• Prev by Date: Re: Lists and rules
• Next by Date: Re: Lists and rules
• Previous by thread: Reconstructing data points from a InterpolatingFunction object
• Next by thread: Re: Reconstructing data points from a InterpolatingFunction object