LL.5 {drc} | R Documentation |
The five-parameter log-logistic function
Description
'LL.5' and 'LL2.5' provide the five-parameter log-logistic function, self starter function and names of the parameters.
Usage
LL.5(fixed = c(NA, NA, NA, NA, NA), names = c("b", "c", "d", "e", "f"), ...)
l5(fixed = c(NA, NA, NA, NA, NA), names = c("b", "c", "d", "e", "f"), ...)
LL2.5(fixed = c(NA, NA, NA, NA, NA), names = c("b", "c", "d", "e", "f"), ...)
Arguments
fixed |
numeric vector. Specifies which parameters are fixed and at what value they are fixed. NAs for parameter that are not fixed. |
names |
a vector of character strings giving the names of the parameters. The default is reasonable. |
... |
Additional arguments (see |
Details
The five-parameter logistic function is given by the expression
f(x) = c + \frac{d-c}{(1+\exp(b(\log(x)-\log(e))))^f}
or in another parameterisation
f(x) = c + \frac{d-c}{(1+\exp(b(\log(x)-e)))^f}
The function is asymmetric for f
different from 1.
Value
See llogistic
.
Note
This function is for use with the function drm
.
Author(s)
Christian Ritz
References
Finney, D. J. (1979) Bioassay and the Practise of Statistical Inference, Int. Statist. Rev., 47, 1–12.
See Also
Related functions are LL.4
and LL.3
.
Examples
ryegrass.m1 <- drm(rootl ~ conc, data = ryegrass, fct = LL.5())
summary(ryegrass.m1)