R/meteZ.R

In mlammens/meteR: Fits and plots macroecological patterns predicted by the Maximum Entropy Theory of Ecology (METE)

#' @title Title of function
#'
#' @description
#' \code{function.name} what it does
#'
#' @details
#' how it works
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#' @param arg description of arg
#' @param arg description of arg
#' @keywords manip
#' @export
#' 
#' @examples
#' #code to run
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#' @return - the type of object that the function returns
#'
#' @author Andy Rominger <ajrominger@@gmail.com>
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##	function to return Z, the normalizing constant of R as well as
##	the simplifying parameters beta and sigma

meteZ <- function(la1,la2,S0,N0,E0) {
	beta <- la1 + la2
	sigma <- la1 + E0*la2
	
	t1 <- S0/(la2*N0)
	t2 <- (exp(-beta) - exp(-beta*(N0+1)))/(1-exp(-beta))
	t3 <- (exp(-sigma) - exp(-sigma*(N0+1)))/(1-exp(-sigma))
	
	Z <- t1*(t2 - t3)
	
	return(Z)
}