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MathGroup Archive 2005

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Re: FinFit question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54850] Re: [mg54816] FinFit question
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Fri, 4 Mar 2005 05:07:46 -0500 (EST)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

I get the same bad result in Version 5.1.1 for both NonlinearFit and FindFit 
(error message indicates NonlinearFit is calling FindFit, i.e., both have error 
message FindFit::nrlnum)

$Version

5.1 for Mac OS X (January 27, 2005)

Needs["Statistics`NonlinearFit`"];

points=
    {{23400,273.2},{6800,298.2},{2400,323.2}};

NonlinearFit[points,B/Log[R/Ro],R,{B,Ro}]

1556.9062702439037/Log[-0.014815259914646271*R]

B/Log[R/Ro] /. FindFit[points,B/Log[R/Ro],{B,Ro},R]

1556.9062702439037/Log[-0.014815259914646271*R]


Bob Hanlon

> 
> From: Zsolt Regály <zs.regaly at icsip.elte.hu>
To: mathgroup at smc.vnet.net
> Date: 2005/03/02 Wed PM 10:29:06 EST
> To: mathgroup at smc.vnet.net
> Subject: [mg54850] [mg54816] FinFit question
> 
> Hi
> 
> I have used Mathematica 4.2 to solve this problem
> 
>     points = {{23400, 273.2}, {6800, 298.2}, {2400, 323.2}};
>     T[R_] = NonlinearFit[points, B/Log[R/Ro], {R}, {B, Ro}];
> 
> wihich gives the result as
> 
>     4021.05/Log[105.49 R]
> 
> 
> That is a good result, but when I try to do the same in Mathematica 5.0 
> I get error messaeges and an other solutions, which is surely bad
>  
>     1556.90/Log[-0.014 R]
> 
> Why doesn't work FindFit for this function in Mathematica 5.0
> 
> Regards,
> Zsolt Regaly (zs.regaly at astro.elte.hu)
> 
> 


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