data <- data.frame(time=c(25, 30, 40, 50),N=c(20, 100, 1000, 900)) model <- function(t, state, parms) { with(as.list(c(state,parms)), { dN <- r*N*(1 - N/K) return(list(dN)) }) } p <- c(r=0.5,K=800) s <- c(N=0.001) f <- fit(data,fun=log,lower=0,legend=FALSE) summary(f)