First-order Compartment Model
Usage
SSfol(Dose, input, lKe, lKa, lCl)
Arguments
Dose
|
a numeric value representing the initial dose.
|
input
|
a numeric vector at which to evaluate the model.
|
lKe
|
a numeric parameter representing the natural logarithm of
the elimination rate constant.
|
lKe
|
a numeric parameter representing the natural logarithm of
the absorption rate constant.
|
lCl
|
a numeric parameter representing the natural logarithm of
the clearance.
|
Description
This selfStart
model evaluates the first-order compartment
function and its gradient. It has an initial
attribute that
will evaluate initial estimates of the parameters lKe
, lKa
,
and lCl
for a given set of data.Value
a numeric vector of the same length as input
. It is the value of
the expression Dose*exp(lKe+lKa-lCl)*(exp(-exp(lKe)*input) -
exp(-exp(lKa)*input))/(exp(lKa) - exp(lKe))
. If all of
the arguments lKe
, lKa
, and lCl
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( Theoph )
Theoph.1 <- Theoph[ Theoph$Subject == 1, ]
SSfol( Theoph.1$Dose, Theoph.1$Time, -2.5, 0.5, -3 ) # response only
lKe <- -2.5
lKa <- 0.5
lCl <- -3
SSfol( Theoph.1$Dose, Theoph.1$Time, lKe, lKa, lCl ) # response and gradient