Re: curve fitting question

*To*: mathgroup at smc.vnet.net*Subject*: [mg115440] Re: curve fitting question*From*: michael partensky <partensky at gmail.com>*Date*: Tue, 11 Jan 2011 00:34:42 -0500 (EST)

You can Solve it for y, Solve[y == a + b (Exp[40*(x + c*y)/d] - 1) - (x + c*y)/e, y] to find y[x]: y = 1/40 ((40 a)/(1 + c/e) - (40 b)/(1 + c/e) - ( 40 x)/((1 + c/e) e) - ( d ProductLog[-(( 40 b c e E^((40 a c e)/(d (c + e)) - (40 b c e)/(d (c + e)) + ( 40 x)/d - (40 c x)/(d (c + e))))/(d (c + e)))])/c. (please double-check if this solution is unique for your range of parameters) This y[x] can be used with FindFit, NonlinearModelFit, etc to find the optimal parameter values. Best Michael Partenskii On Mon, Jan 10, 2011 at 2:34 AM, Michael B. Heaney <mheaney at alum.mit.edu>wrote: > Hi, > > I have data in (x,y) pairs. I have an equation: > > y= a +b (Exp[40*(x + c*y)/d] - 1) - (x +c*y)/e > > where a,b,c,d, and e are fitting parameters. > > Note that this equationcannot be put in the form y=f(x). > > How do I fit this equation to my x,y data? > > Thanks, > > Michael > > >