R/vb_lengths.R

In lhmixr: Fit Sex-Specific Life History Models with Missing Classifications

#' @title von Bertalanffy growth function.
#'
#' @description \code{vb_lengths} returns the predicted length-at-age for given named set of parameters for the von Bertalanffy growth function:
#' \deqn{l = L_{\infty} (1 - e^{-k(a - t_0)})}
#'
#' @param theta A numeric vector with named values "linf", "k", "t0".
#' @param age A numeric vector of ages.
#' @return Predicted length-at-age.
#' @examples
#' vb_lengths(theta = c("linf" = 30,"k" = 0.2,"t0" = -1), age = 0:10)
#' @export

vb_lengths <- function(theta, age) {
 pred_length <- theta["linf"] * (1 - exp(-theta["k"] * (age - theta["t0"])))
 return(pred_length)
}