Re: Nonlinear Fit Problem
- To: mathgroup at smc.vnet.net
- Subject: [mg7285] Re: Nonlinear Fit Problem
- From: junkin <junkin at augustus0.physics.unc.edu>
- Date: Thu, 22 May 1997 09:19:31 -0400 (EDT)
- Organization: Duke University, Durham, NC, USA
- Sender: owner-wri-mathgroup at wolfram.com
I have included a simple example below just to demonstrate the problems
that I have encountered with the NonlinearFit routine (in the
Statistics'NonlinearFit' package). As you can clearly see, the addition
of a constant gives an erronious fit. Is there a patch available, or is
this a feature that I do not understand? I am using Mathmatica version
3.0.0.0.
Thank you,
David Junkin
In[82]:=
data7={{1,1},{2,2.1},{3,3.1},{4,4.3},{5,5.4}}
datafit=NonlinearFit[data7,
(a + 1) - 1/6 b x + 1/120 c x^2 ,{x}, {a,b,c}]
datafit2=NonlinearFit[data7,
a - 1/6 b x 1/120 c x^2 ,{x}, {a,b,c}]
Out[82]=
{{1,1},{2,2.1},{3,3.1},{4,4.3},{5,5.4}}
Out[83]=
0.9800 + 1.014285 x + 0.01428 x^2
Out[84]=
-0.01991.01428 x + 0.01428 x^2