Hi Rainer, It is very simple to specify the constraints (linear or nonlinear) in "alabama" . They are specified in a function called `hin', where the constraints are written such that they are positive. Your two nonlinear constraints would be written as follows:
hin <- function(x, LAI) { h <- rep(NA, 2) h[1] <- LAI^x[2] / x[3] + x[1] h[2] <- 1 - x[1] - LAI^x[2] / x[3] h } Please take a look at the help page. If it is still not clear, you can contact me offline. Best, Ravi Ravi Varadhan, Ph.D. (Biostatistics), Ph.D. (Environmental Engg) Associate Professor, Department of Oncology Division of Biostatistics & Bionformatics Sidney Kimmel Comprehensive Cancer Center Johns Hopkins University 550 N. Broadway, Suite 1111-E Baltimore, MD 21205 410-502-2619 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.