The R Project SVN – R – Diff – /trunk/src/library/stats/man/SSgompertz.Rd

 % File src/library/stats/man/SSgompertz.Rd
 % Part of the R package, https://www.R-project.org
-% Copyright 1995-2007 R Core Team
+% Copyright 1995-2017 R Core Team
 % Distributed under GPL 2 or later
 \name{SSgompertz}
 \title{Self-Starting Nls Gompertz Growth Model}
 \usage{
 \author{Douglas Bates}
 \seealso{\code{\link{nls}}, \code{\link{selfStart}}
+}
 \examples{
 DNase.1 <- subset(DNase, Run == 1)
-SSgompertz(log(DNase.1$conc), 4.5, 2.3, 0.7)   # response only
+SSgompertz(log(DNase.1$conc), 4.5, 2.3, 0.7)  # response only
-Asym <- 4.5; b2 <- 2.3; b3 <- 0.7
+local({  Asym <- 4.5; b2 <- 2.3; b3 <- 0.7
-SSgompertz(log(DNase.1$conc), Asym, b2, b3) # response and gradient
+  SSgompertz(log(DNase.1$conc), Asym, b2, b3) # response _and_ gradient
+})
 print(getInitial(density ~ SSgompertz(log(conc), Asym, b2, b3),
                  data = DNase.1), digits = 5)
 ## Initial values are in fact the converged values
 fm1 <- nls(density ~ SSgompertz(log(conc), Asym, b2, b3),
            data = DNase.1)
 summary(fm1)
+plot(density ~ log(conc), DNase.1, # xlim = c(0, 21),
+     main = "SSgompertz() fit to DNase.1")
+ux <- par("usr")[1:2]; x <- seq(ux[1], ux[2], length.out=250)
+lines(x, do.call(SSgompertz, c(list(x=x), coef(fm1))), col = "red", lwd=2)
+As <- coef(fm1)[["Asym"]]; abline(v = 0, h = 0, lty = 3)
+axis(2, at= exp(-coef(fm1)[["b2"]]), quote(e^{-b[2]}), las=1, pos=0)
+}
 \keyword{models}

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