Fit data

*To*: mathgroup at smc.vnet.net*Subject*: [mg124666] Fit data*From*: Miguel Camino <m.caminouni at hotmail.com>*Date*: Mon, 30 Jan 2012 05:09:48 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi, I'm new in this forum and with Mathematica..I've got 2 questions;Is too much? 1. I've to regress some data with a formula that I've implemented.This is an Example of my data and this is my formula:sigma=a*pc^(0.618)*tc*(1+omega)^c*(1-tr)^dtr, omega, tc, pc sigma0.703784817, 0.310237474, 361.0989249, 34.97280104, 12.410.710106871, 0.310283818, 361.1126025, 34.94104003, 12.140.715649046, 0.310330225, 361.1262985, 34.90923611, 11.770.720912444, 0.310376694, 361.1400131, 34.87738919, 11.520.726476477, 0.31043254, 361.1564951, 34.83911601, 11.30.731293672, 0.310479148, 361.1702505, 34.80717419, 11I used this formulafit = NonlinearModelFit[data, a*pc^(0.618)*tc^b*(1 + omega)^c*(1 - Tr)^d, {a, b, c, d}, {Tr, omega, tc, pc}]and I try to calculate best {a,b,c,d}. 2. I don't know if 0.618 is the best value. Is thes a way to find the best number that Fit my data?Thanks and sorry for two questions!M.