R/lodds.R

In OncoBayes2: Bayesian Logistic Regression for Oncology Dose-Escalation Trials

#' @rdname lodds
#' @name lodds
#' 
#' @title Logit (log-odds) and inverse-logit function.
#'
#' @description
#' Calculates the logit (log-odds) and inverse-logit.
#'
#' @param mu A numeric object with probabilies, with values in the in
#' the range [0,1]. Missing values (NAs) are allowed.
#' @param eta A numeric object with log-odds values, with values in
#' the range [-Inf,Inf]. Missing values (NAs) are allowed.
#'
#' @details Values of mu equal to 0 or 1 will return -Inf or Inf
#' respectively.
#' 
#' @return A numeric object of the same type as mu and eta containing
#' the logits or inverse logit of the input values.  The logit and
#' inverse transformation equates to
#' 
#' \deqn{\mbox{logit}(\mu) = \log(\mu/(1-\mu))}{logit(\mu) = log(\mu/(1-\mu))}
#' \deqn{\mbox{logit}^{-1}(\eta)= \exp(\eta)/(1 + \exp(\eta)).}{logit^-1(\eta) = exp(\eta)/(1 + exp(\eta)).}
#' 
#' @examples
#' logit(0.2)
#' inv_logit(-1.386)
#' 
NULL
bin <- binomial()

#' @export
#' @rdname lodds
logit <- bin$linkfun

#' @export
#' @rdname lodds
inv_logit <- bin$linkinv