Re: NonlinearFit for specific data
- To: mathgroup at smc.vnet.net
- Subject: [mg117848] Re: NonlinearFit for specific data
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Fri, 1 Apr 2011 02:36:17 -0500 (EST)
That model appears to fit your data very poorly. Perhaps you should look at a different model. data2 = {{0, 773.59}, {30, 2351.12}, {60, 4205.8}, {90, 4222.69}, {120, 4222.69}, {150, 704.328}, {180, 1388.28}, {210, 1388.28}, {240, 1821.23}, {270, 1821.23}, {300, 754.109}, {330, 773.59}, {360, 773.59}}; Partition[Table[ param = Array[a, n + 1]; model = Total[param*x^Range[0, n]]; fit = FindFit[data2, model, param, x]; Plot[model /. fit, {x, 0, 360}, PlotRange -> {500, 5000}, Frame -> True, Axes -> False, Epilog -> {Text["n = " <> ToString[n], Scaled[{.8, .9}]], Red, AbsolutePointSize[4], Point[data2]}], {n, 2, 10}], 3] // Grid Bob Hanlon ---- Alexandre Souza <costamfix at gmail.com> wrote: ============= Dear Group, I have the following data : data2 = { {0, 773.59},{30, 2351.12},{60, 4205.8}, {90, 4222.69},{120, 4222.69},{150, 704.328}, {180, 1388.28},{210, 1388.28},{240, 1821.23},{270, 1821.23},{300, 754.109},{330, 773.59},{360, 773.59}}; I want the following curve fit : NonlinearFit[data2, Exp[ a + b x + c x^2], x, {a, b, c}] Unfortunatelly I get some "FindFit::sszero FindMinimum::sszero" message, and the given result is ackward. I also tried FindFit and NonlinearRegress without success. Any comment would be very welcome. Alex