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Re: How to get range of InterpolatingFunction ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg64035] Re: [mg64015] How to get range of InterpolatingFunction ?
  • From: "Carl K. Woll" <carlw at wolfram.com>
  • Date: Sat, 28 Jan 2006 02:23:50 -0500 (EST)
  • References: <200601271013.FAA19043@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

kowald at molgen.mpg.de wrote:
> Hello everybody,
> 
> I wonder how I can find out the range for which an
> InterpolatingFunction object is valid ?
> If I have   {{y -> InterpolatingFunction[{{0., 3.}}, <>]}} , how can I
> extract the 0 and the 3 ??
> 
> Many thanks,
> 
>                Axel

There is a package that lets you extract this information. For example:

In[1]:=
if = FunctionInterpolation[x^2, {x, 0, 3}]

Out[1]=
InterpolatingFunction[{{0.,3.}},<>]

Needs["DifferentialEquations`InterpolatingFunctionAnatomy`"]

In[3]:=
InterpolatingFunctionDomain[if]

Out[3]=
{{0.,3.}}

If you take a look at the package, you find that you can dispense with 
the package and find the domain directly. Quitting the kernel and 
starting over:

In[1]:=
if = FunctionInterpolation[x^2, {x, 0, 3}]

Out[1]=
InterpolatingFunction[{{0.,3.}},<>]

Find domain directly:

In[2]:=
if["Domain"[]]

Out[2]=
{{0.,3.}}

There are five other pieces of information about an interpolating 
function that can be extracted in this manner. Check out the package. It 
lives in AddOns/ExtraPackages/DifferentialEquations.

Carl Woll
Wolfram Research


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