1. Have you considered "nls" or "optim"? The documentation for both includes useful examples.
2. What do your Y values represent? The almost universal standard today is maximum likelihood estimation. If you tell us what the Y values are, someone might help you write a likelihood function that could then be maximized using "optim". 3. I notice this is the third post I've answered for you in the past month. I've been so busy recently, I tend to limit myself only to posts that are several days old for which I have not seen a reply. I believe you might get quicker and more useful replies to your questions if you please read and try to follow the posting guide! "http://www.R-project.org/posting-guide.html". Good luck. spencer graves Haibo Huang wrote: > I want to fit a Log-Normal CDF function between two > variables, and estimate the parameters. Is there any > package/functions designed for this purpose? > > Basically, I have data for Y and X, and I suspect the > relationship between Y and X is Y = CDF Log-Normal > (X), and I want to run this regression to verify this > and estimate the parameters. Anyone has any thoughts? > > Any input is valuable to me, so please do not hesitate > to share your thoughts. Thank you! > > Ed. > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html -- Spencer Graves, PhD Senior Development Engineer PDF Solutions, Inc. 333 West San Carlos Street Suite 700 San Jose, CA 95110, USA [EMAIL PROTECTED] www.pdf.com <http://www.pdf.com> Tel: 408-938-4420 Fax: 408-280-7915 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html