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MathGroup Archive 2004

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Re: Function interpolation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg45355] Re: [mg45336] Function interpolation
  • From: Yasvir Tesiram <tesiramy at omrf.ouhsc.edu>
  • Date: Fri, 2 Jan 2004 04:23:44 -0500 (EST)
  • References: <200401011054.FAA17763@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,
See the notes for Table in Help or evaluate ?Table in your Notebook.

Suppose you have two lists of x and y values;

In[2]:= x={0,1,2,3,4,5}

Out[2]= {0, 1, 2, 3, 4, 5}

In[3]:= y={0,2,4,8,16,32}

Out[3]= {0, 2, 4, 8, 16, 32}

Now you can make your pairs.

In[4]:= t1={x,y}//Transpose

Out[4]= {{0, 0}, {1, 2}, {2, 4}, {3, 8}, {4, 16}, {5, 32}}

Make an InterpolatingFunction

In[7]:= newfunc=Interpolation[t1]

Out[7]= InterpolatingFunction[{{0, 5}}, <>]

In[8]:= newfunc[2.3]

Out[8]= 4.899


Cheers
Yas



On Thu, 1 Jan 2004 fernandoronci at hotmail.com wrote:

> Hi,
>
> I'm new to Mathematica and need some hints on how to derive (or
> estimate) a function from a given set of discrete x/y values.
> I know Mathematica can do this but I don't know how.
> For example, I tried to create a table of x/y values, then assign the
> approximated funcion to 'newfunction' and test it by calling it with
> 2.3 as argument, but it failed as follows (I couldn't even figure out
> how to build the table):
>
> Table = [{0, 0}, {1, 2}, {2, 4}, {3, 8}, {4, 16}, {5, 32}]
> newfunction = Interpolation[%]
> newfunction[2.3]
>
> Syntax::"sntxf": "Table =" cannot be followed by "[{0, 0}, {1, 2}, {2,
> 4}, {3, 8}, {4, 16}, {5, 32}]".
> Table = [{0, 0}, {1, 2}, {2, 4}, {3, 8}, {4, 16}, {5, 32}]
>
> BTW, I'm working with Mathematica 4.
> Help appreciated.
> Thank you,
>
> Fernando Ronci
> E-mail: fernandoronci at hotmail.com
>


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