Re: FinFit question
- To: mathgroup at smc.vnet.net
- Subject: [mg54834] Re: [mg54816] FinFit question
- From: DrBob <drbob at bigfoot.com>
- Date: Fri, 4 Mar 2005 05:07:33 -0500 (EST)
- References: <200503030329.WAA21066@smc.vnet.net>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
Do it this way:
<< Statistics`NonlinearFit`
points = {{23400, 273.2}, {6800, 298.2}, {2400, 323.2}};
T[R_] = NonlinearFit[points, B/(Log[R] - logRo), {R}, {B, logRo}]
T /@ points[[All, 1]]
4021.0588923624114/
(4.658619219272381 + Log[R])
{273.186, 298.225, 323.188}
The original form (using Ro) is asking for trouble because you have (in your mind alone) an assumption that Ro>0. There is no such restriction on logRo.
Bobby
On Wed, 2 Mar 2005 22:29:06 -0500 (EST), Zsolt Regály <zs.regaly at icsip.elte.hu> wrote:
> 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)
>
>
>
>
--
DrBob at bigfoot.com
www.eclecticdreams.net
- References:
- FinFit question
- From: Zsolt Regály <zs.regaly@icsip.elte.hu>
- FinFit question