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Re: Interpolation problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33490] Re: [mg33435] Interpolation problem
  • From: BobHanlon at aol.com
  • Date: Fri, 22 Mar 2002 04:08:49 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

In a message dated 3/21/02 10:34:54 AM, peter.weijnitz at mic.ericsson.se writes:

>If you use Intepolation on these data, it looks strange, why?
>
>mm={{0.8,1/0.8},{0.9,1/0.9},{2.8,1/2.8},{5.8,1/5.8},{5.9,1/5.9}};
>
>I did:
>
>imm=Interpolation[mm];
>
>Plot[imm[t],{t,0.8,5.9},PlotRange->All,
>  Epilog->Evaluate[mm/.{a_,b_}->{AbsolutePointSize[10],Point[{a,b}]}]];
>
>The resulting curve goes through all points but it deviates between
>points?
>
>I have tred different intepolationorder values.
>

mm={{0.8,1/0.8},{0.9,1/0.9},{2.8,1/2.8},
      {5.8,1/5.8},{5.9,1/5.9}};

imm=Interpolation[mm,
 
      InterpolationOrder->Length[mm]-1];

Plot[imm[t],{t,0.8,5.9},
    PlotRange->All,
    Epilog->{AbsolutePointSize[6],Point/@mm}];

ip = InterpolatingPolynomial[mm,t]//Expand

Plot[ip,{t,0.8, 5.9},
 
    PlotRange->All,
 
    Epilog->{AbsolutePointSize[6],Point/@mm}];


Bob Hanlon
Chantilly, VA  USA


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