[R] help on sigmoid curve fitting

Hi list, I was wondering how I should go about fitting a sigmoid curve to a dataset. More specifically how I estimate parameters a and b in the following equation: 1 / 1+exp(-(x-a)*b) with b the steepness of the sigmoid curve and a the shift of the center of the sigmoid curve relative to

Re: [R] help on sigmoid curve fitting

you can use nls: see ?nls and its example. HTH. On 3/16/07, Hufkens Koen [EMAIL PROTECTED] wrote: Hi list, I was wondering how I should go about fitting a sigmoid curve to a dataset. More specifically how I estimate parameters a and b in the following equation: 1 / 1+exp(-(x-a)*b)