The R Project SVN R

Rev

Rev 68948 | Rev 85990 | Go to most recent revision | Show entire file | Ignore whitespace | Details | Blame | Last modification | View Log | RSS feed

Rev 68948 Rev 73628
Line 1... Line 1...
1 
% File src/library/stats/man/SSweibull.Rd
 1 
% File src/library/stats/man/SSweibull.Rd
2 
% Part of the R package, https://www.R-project.org
 2 
% Part of the R package, https://www.R-project.org
3 
% Copyright 1995-2007 R Core Team
 3 
% Copyright 1995-2017 R Core Team
4 
% Distributed under GPL 2 or later
 4 
% Distributed under GPL 2 or later
5 
 
 5 
 
6 
\name{SSweibull}
 6 
\name{SSweibull}
7 
\title{Self-Starting Nls Weibull Growth Curve Model}
 7 
\title{Self-Starting Nls Weibull Growth Curve Model}
8 
\usage{
 8 
\usage{
Line 34... Line 34...
34 
  attached as an attribute named \code{gradient}.
 34 
  attached as an attribute named \code{gradient}.
35 
}
 35 
}
36 
\details{
 36 
\details{
37 
  This model is a generalization of the \code{\link{SSasymp}} model in
 37 
  This model is a generalization of the \code{\link{SSasymp}} model in
38 
  that it reduces to \code{SSasymp} when \code{pwr} is unity.
 38 
  that it reduces to \code{SSasymp} when \code{pwr} is unity.
39 
  }
 39 
}
40 
\author{Douglas Bates}
 40 
\author{Douglas Bates}
41 
\references{
 41 
\references{
42 
  Ratkowsky, David A. (1983), \emph{Nonlinear Regression Modeling},
 42 
  Ratkowsky, David A. (1983), \emph{Nonlinear Regression Modeling},
43 
  Dekker. (section 4.4.5)
 43 
  Dekker. (section 4.4.5)
44 
}
 44 
}
45 
\seealso{\code{\link{nls}}, \code{\link{selfStart}}, \code{\link{SSasymp}}
 45 
\seealso{\code{\link{nls}}, \code{\link{selfStart}}, \code{\link{SSasymp}}
46 
}
 46 
}
47 
\examples{
 47 
\examples{
48 
Chick.6 <- subset(ChickWeight, (Chick == 6) & (Time > 0))
 48 
Chick.6 <- subset(ChickWeight, (Chick == 6) & (Time > 0))
49 
SSweibull(Chick.6$Time, 160, 115, -5.5, 2.5)   # response only
 49 
SSweibull(Chick.6$Time, 160, 115, -5.5, 2.5)   # response only
50 
Asym <- 160; Drop <- 115; lrc <- -5.5; pwr <- 2.5
 50 
local({ Asym <- 160; Drop <- 115; lrc <- -5.5; pwr <- 2.5
51 
SSweibull(Chick.6$Time, Asym, Drop, lrc, pwr)  # response and gradient
 51 
  SSweibull(Chick.6$Time, Asym, Drop, lrc, pwr) # response _and_ gradient
- 
 
 52 
})
52 
getInitial(weight ~ SSweibull(Time, Asym, Drop, lrc, pwr), data = Chick.6)
 53 
getInitial(weight ~ SSweibull(Time, Asym, Drop, lrc, pwr), data = Chick.6)
53 
## Initial values are in fact the converged values
 54 
## Initial values are in fact the converged values
54 
fm1 <- nls(weight ~ SSweibull(Time, Asym, Drop, lrc, pwr), data = Chick.6)
 55 
fm1 <- nls(weight ~ SSweibull(Time, Asym, Drop, lrc, pwr), data = Chick.6)
55 
summary(fm1)
 56 
summary(fm1)
- 
 
 57 
## Data and Fit:
- 
 
 58 
plot(weight ~ Time, Chick.6, xlim = c(0, 21), main = "SSweibull() fit to Chick.6")
- 
 
 59 
ux <- par("usr")[1:2]; x <- seq(ux[1], ux[2], length.out=250)
- 
 
 60 
lines(x, do.call(SSweibull, c(list(x=x), coef(fm1))), col = "red", lwd=2)
- 
 
 61 
As <- coef(fm1)[["Asym"]]; abline(v = 0, h = c(As, As - coef(fm1)[["Drop"]]), lty = 3)
56 
}
 62 
}
57 
\keyword{models}
 63 
\keyword{models}