Re: findfit or solve?
- To: mathgroup at smc.vnet.net
- Subject: [mg55021] Re: [mg55013] findfit or solve?
- From: "Christoph Lhotka" <lhotka at astro.univie.ac.at>
- Date: Thu, 10 Mar 2005 05:24:20 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
As you can see in the help browser (FindFit) ...
FindFit[data,expr,{par1,p1},par2,p2},...},vars] starts the search for a fit
with {pa11->p1, par2->p2,...}..
So in your example define the data:
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}};
and the model:
model = model(a,b,c,d,e,t)
(use your model, I do not see, the inner structure.)
... and then just type ...
FindFit[data, model, {{a, 176}, {b, 160}, {c, 0.1}, {d, 14}, {e, 1.2}}, t]
and it will work.
There is a very comprehensive and detailed documentation under Mathematica
V5.0 Advanced Documentation (Help Browser)
with best wishes
C.L.
On Wed, 9 Mar 2005 06:34:39 -0500 (EST)
"Tegla Bela" <spiller at hotmail.co.jp> wrote:
> 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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