ch16.R
In ISwR: Introductory Statistics with R

t <- 0:10
y <- rnorm(11, mean=5*exp(-t/5), sd=.2)
plot(y ~ t)
if (.make.epsf) dev.copy2eps(file="nonlin-sim.ps")
nlsout <- nls(y ~ A*exp(-alpha*t), start=c(A=2, alpha=0.05))
summary(nlsout) 
attach(subset(juul2, age<20 & age>5 & sex==1))
plot(height ~ age)
if (.make.epsf) dev.copy2eps(file="juul-a-h.ps")
plot(log(5.3-log(height))~age)
if (.make.epsf) dev.copy2eps(file="gomp-dif.ps")
lm(log(5.3-log(height))~age)
fit <- nls(height~alpha*exp(-beta*exp(-gamma*age)),
           start=c(alpha=exp(5.3),beta=exp(0.42),gamma=0.15))
summary(fit)
plot(age, height)
newage <- seq(5,20,length=500)
lines(newage, predict(fit,newdata=data.frame(age=newage)),lwd=2)
if (.make.epsf) dev.copy2eps(file="gompertz.ps")

fit <- nls(log(height)~log(alpha*exp(-beta*exp(-gamma*age))),
start=c(alpha=exp(5.3),beta=exp(.12),gamma=.12))
summary(fit)
plot(age, log(height))
lines(newage, predict(fit,newdata=data.frame(age=newage)),lwd=2)
if (.make.epsf) dev.copy2eps(file="log-gompertz.ps")
# count quoted in text, subtract 1 for SSD()
length(ls(pattern="SS.*", "package:stats"))-1
summary(nls(height~SSgompertz(age, Asym, b2, b3))) 
cf <- coef(nls(height ~ SSgompertz(age, Asym, b2, b3)))
summary(nls(log(height) ~ 
               log(as.vector(SSgompertz(age,Asym, b2, b3))),
            start=as.list(cf)))
par(mfrow=c(3,1))
plot(profile(fit))
if (.make.epsf) dev.copy2eps(file="gomp-prof.ps")
confint(fit)
confint.default(fit)
rm(list=ls())
while(search()[2] != "package:ISwR") detach()