NonlinearFit - Logistic Function-CalcCenter3

*To*: mathgroup at smc.vnet.net*Subject*: [mg60443] NonlinearFit - Logistic Function-CalcCenter3*From*: Oddur Bjarnason <oddur.bjarnason at broadpark.no>*Date*: Fri, 16 Sep 2005 03:50:36 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I can fit a logistic function of the form a/(1 + b*Exp[-c*t]) to the data points -0.06 -0.05 0.97 -4.2 1.99 -9.79 3 -12.44 3.99 -14.57 5.92 -16.85 7.87 -17.27 11.89 -17.69 15.8 -17.74 19.74 -17.77 23.67 -18.19 I can not fit the same function to the data points -0.08 0.05 0.96 -3.19 1.93 -6.4 2.98 -10.32 3.97 -11.8 5.92 -13.98 7.88 -14.12 11.85 -15.34 15.79 -14.61 19.7 -15.43 23.67 -15.83 I have tried to do it with Mathematica without success. I have no problem when I use a progam called CurveExpert. Regards, Oddur Bjarnason