w3 {drc} | R Documentation |
'w3' provides the three-parameter Weibull function, self starter function and names of the parameters.
w3(fixed = c(NA, NA, NA), names = c("b", "d", "e"), useDer = FALSE)
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! |
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 weibull
.
This function is for use with the function multdrc
.
Christian Ritz
Related functions are w4
and weibull
.
## Fitting a three-parameter Weibull model model1 <- multdrc(FA, fct = w3()) model1 rm(model1)