R/modelfunction_sigmoid_inverse.R

In ropensci/DoOR.functions: Integrating Heterogeneous Odorant Response Data into a Common Response Model: A DoOR to the Complete Olfactome

# inverse Logistic Model
# 
# inverse Logistic Model
# 
# expression : xmid - scal * log((Asym / input) - 1)
# 
# @param input numeric vector of data values
# @param parms numeric vector, parameters with given names: "Asym", "xmid",
# "scal"
# @seealso \code{\link{SSlogis}}
# @references Jose Pinheiro and Douglas Bates
# @keywords math
# @examples
# 
# x <- seq(0.1,1,length=20)
# y <- modelfunction_sigmoid_inverse(input = x, parms = c(Asym = 2, xmid = 0.2, 
#                                                         scal = 0.3) )
# plot(x,y)
# 
modelfunction_sigmoid_inverse <- function(input, parms) {
  subfun <- function(input) {
    exp1  <- (parms["Asym"] / input) - 1
    if (exp1[1] <= 0 | is.na(exp1[1])) { 
      return(NA)
    } else {
      return(parms["xmid"] - parms["scal"] * log((parms["Asym"] / input) - 1))
    }
  }
  return(vapply(input, subfun, numeric(1)))
}