Re: Fit
- To: mathgroup at smc.vnet.net
- Subject: [mg7044] Re: [mg7011] Fit
- From: Allan Hayes <hay at haystack.demon.co.uk>
- Date: Sat, 3 May 1997 22:04:39 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
WANNKE Michael <wannkem8 at cti.ecp.fr>
[mg7011] Fit
>if I use the following command line:
>fitted = Fit[database,{1,x,x^2},x]
>Mathematica returns a fixed expression with x as variable. The
>problem is that now x is the only variable which can be used:
>Plot[fitted,{x,0,1000}] returns the right graph
>Plot[fitted, {z,0,1000}] returns an error!
>How can I fit my database in order to get a function (style >f[x]:=...)?
Michael,
data = Table[{x,Cos[x]+Random[]/3},{x,0,5}];
fx = Fit[data, {1,x,x^2},x]; (*a polynomial in x*)
f[x_] = fx; (* = not := , so that fx is evaluated*)
Or, in one step,
f[x_] = Fit[data, {1,x,x^2},x];
Check
Plot[f[z],{z,0,4},
Epilog->{PointSize[.02],Point/@data},PlotRange->All]
Allan Hayes
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk