Re: NonlinearFit
- To: mathgroup at smc.vnet.net
- Subject: [mg42150] Re: NonlinearFit
- From: "jfa" <jfa.news.invalid at web2news.net>
- Date: Sat, 21 Jun 2003 02:49:30 -0400 (EDT)
- References: <bcrrkf$1@smc.vnet.net>
- Reply-to: "jfa" <jf.annoo+s1pa0mlcover at bdpme.fr>
- Sender: owner-wri-mathgroup at wolfram.com
Rees wrote:
> Hi,
>
> Please could someone assist me in curve fitting.
>
> I have the following x,y data
>
> data = {{0.1,0.113387476}, {0.2, 0.194633152}, {0.3,
> 0.252848224}, {0.4, 0.294561145}, {0.5,
> 0.324449759}, {0.6, 0.345865887}, {0.7,
> 0.361211213}, {0.8, 0.37220662}, {0.9,
> 0.380085173}, {1.0, 0.385730403}};
>
> Now I wish to fit an exponential curve of the form below to it:
>
> c*[1-Exp(-3x/a]
>
> where c and a are parameters to be determined.
>
> I tried the following but it doesn't work:
>
> NonlinearFit[data, c*(1 - Exp(-3*x1/a)), {x1}, {c, a}]
>
> Please advise.
>
> Thanks is advance
>
> Rees
It does work if you use brackets instead of parentheses with Exp :
In[1]:=
<<Statistics`NonlinearFit`
data={{0.1,0.113387476}, {0.2, 0.194633152},
{0.3, 0.252848224}, {0.4, 0.294561145},
{0.5, 0.324449759}, {0.6, 0.345865887},
{0.7, 0.361211213}, {0.8, 0.37220662},
{0.9, 0.380085173}, {1.0, 0.385730403}};
nlf=NonlinearFit[data, c*(1 - Exp[-3*x1/a]), {x1}, {c, a}]
Out[1]=
0.40000000043347517*(1 - E^(-3.33333333010406*x1))
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