Asymptotic Regression Model through the Origin
Usage
SSasympOrig(input, Asym, lrc)
Arguments
input
|
a numeric vector of values at which to evaluate the model.
|
Asym
|
a numeric parameter representing the horizontal asymptote.
|
lrc
|
a numeric parameter representing the natural logarithm of
the rate constant.
|
Description
This selfStart
model evaluates the asymptotic regression
function through the origin and its gradient. It has an
initial
attribute that will evaluate initial estimates of the
parameters Asym
and lrc
for a given set of data.Value
a numeric vector of the same length as input
. It is the value of
the expression Asym*(1 - exp(-exp(lrc)*input))
. If all of
the arguments Asym
and lrc
are
names of objects, as opposed to expressions or explicit numerical
values, the gradient matrix with respect to these names is attached as
an attribute named gradient
.Author(s)
Jose Pinheiro and Douglas BatesSee Also
nls
, selfStart
Examples
library( lme )
data( Loblolly )
Lob.329 <- Loblolly[ Loblolly$Seed == "329", ]
SSasympOrig( Lob.329$age, 100, -3.2 ) # response only
Asym <- 100
lrc <- -3.2
SSasympOrig( Lob.329$age, Asym, lrc ) # response and gradient