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