Three-parameter log-logistic function

A three-parameter log-logistic function with lower limit fixed at 0.

Usage

LL.3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), ...)

l3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), ...)

Arguments

fixed

numeric vector of length 3, specifying fixed parameters (use NA for non-fixed parameters).

names

character vector of length 3, specifying the names of the parameters (default: b, d, e).

...

additional arguments to llogistic.

Value

See llogistic.

Details

The three-parameter log-logistic function is given by the expression $$f(x) = \frac{d}{1+\exp(b(\log(x)-\log(e)))}$$

See also

LL.2, LL.4, LL.5, llogistic

Author

Christian Ritz

Examples

ryegrass.model1 <- drm(rootl ~ conc, data = ryegrass, fct = LL.3())