drc (version 1.2-0)

W1.3: The three-parameter Weibull functions

Description

'W1.3' provides the three-parameter Weibull function, self starter function and names of the parameters.

Usage

W1.3(fixed = c(NA, NA, NA), names = c("b", "d", "e"))
  
  W2.3(fixed = c(NA, NA, NA), names = c("b", "d", "e"))

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.

Value

• See weibull1.

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 W1.4 and weibull1.

Examples

## Fitting a three-parameter Weibull model
model1 <- multdrc(ryegrass, fct = W1.3())
model1

rm(model1)