Dear all, I am looking for a R-function that performs nonlinear constraint optimization (where the objective function and the constraints are allowed to be nonlinear). More specifically, I am trying to figure out whether there is an equivalent function of NAG fortran library' "E04UCF" or matlab's "fmincon" in R. Any help is greatly appreciated. Thank you, Sunduz PS: fmincon is described at http://www.mathworks.com/access/helpdesk/help/toolbox/optim/optim.shtml?BB=1