Re: Curve-fitting/data analysis question...

*To*: mathgroup at smc.vnet.net*Subject*: [mg73324] Re: Curve-fitting/data analysis question...*From*: dh <dh at metrohm.ch>*Date*: Mon, 12 Feb 2007 05:03:42 -0500 (EST)*References*: <eqmcfh$bdv$1@smc.vnet.net>

Hi noname, here is an example: fun = x1 Exp[-x3(x - x2) Boole[x > x2]]; res = FindFit[d, fun, {x1, x2, x3}, x] funr = fun /. res; Plot[funr, {x, 0, 2}] Daniel sherifffruitfly wrote: > Hi all, > > I've got some data that is approximately constant, c, over an > interval, and then drops off like -(a exp(b x)). > > How can I determine when the constant part ends, and the negative > exponential begins in Mathematica? I can eyeball it on a graph, but I'd much > prefer to have a principled Mathematica routine settle the question. Once > that's settled, it should be straightforward to determine the > exponential's parameters via some curve-fitting routine or other. > > Thanks for any suggestions, > > cdj > >