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findfit or solve?

• To: mathgroup at smc.vnet.net
• Subject: [mg55013] findfit or solve?
• From: "Tegla Bela" <spiller at hotmail.co.jp>
• Date: Wed, 9 Mar 2005 06:34:39 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Greetings to everybody, 

I have found a model and I would like to use Mathematica for the data under 
the model. The model is as follows:

= h1 - ((2 * (h1 - h$B&H(B)) / ((EXP(s0 * (t -$B&H(B))) + (EXP(s1 * (t -$B&H(B)))))

data = {{6.968, 117.1}, {7.967, 123.3}, {9.046, 
      129.4}, {9.982, 134.6}, {10.951,
       139.2}, {11.973, 145.2}, {13.021, 151.1}, {13.892, 159.9}, {
      14.888, 167.8}, {15.858, 171.9}, {16.857, 175.7}, {17.854, 177.2}, {
      18.724, 175.6}};

I have managed to do it with nonlinear least-square fitting in other 
program. But not working for me in Mathematica. (I do not know how to give 
initial values to have the five unknown parameters estimated) These are the 
initial values that I would like to use: a=176, b=160, c=0.1, d=14, e=1.2 
(t is the age, first value in each pair of the data)

Does anybody have idea how it can be done? Any help is appreciated.

Spiller

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  • Re: findfit or solve?
    • From: DrBob <drbob@bigfoot.com>