inst/non_lin_models/Mod_betap.R

In sars: Fit and Compare Species-Area Relationship Models Using Multimodel Inference

#Beta-P function (cumulative)
model = list(
  name = c("Beta-P cumulative"),
  formula = expression(S == d*(1-(1+(A/c)^z)^-f)),
  exp = expression(d*(1-(1+(A/c)^z)^-f)),
  shape = "sigmoid",
  asymp = function(pars)pars["d"],
  parLim  =  c("Rplus","R","R","R"),
  #initial values function
  init = function(data){c(max(data$S)+1,.5,.5,.5)}
)