drc (version 1.0-3)

w3: The three-parameter Weibull function

Description

'w3' provides the three-parameter Weibull function, self starter function and names of the parameters.

Usage

w3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), useDer = FALSE)

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.

useDer

logical. If TRUE derivatives are supplied, otherwise they are not supplied. Not implemented!

Value

• See weibull.

Details

The three-parameter Weibull model is given by the expression $$f(x) = 0 + (d-0)\exp(-\exp(b(\log(x)-e))).$$ The function is asymmetric about the inflection point, that is the parameter $\exp(e)$.

See Also

Related functions are w4 and weibull.

Examples

## Fitting a three-parameter Weibull model
model1 <- multdrc(FA, fct = w3())
model1

rm(model1)