R/euclidean.R

In fengye0907/LAB3: Package for lab3 in Advanced Programming in R

#' euclidean
#'
#' \code{euclidean} The Euclidian algorithm can find the greatest common divisor of two numbers.
#'
#' @param a Integer number
#' @param b Interger number
#'
#' @return An interger represents the greatest common divisor of two numbers.
#'
#' @references \url{https://en.wikipedia.org/wiki/Euclidean_algorithm}
#'
#' @export

euclidean <- function(a, b)
{
  rk_1 <- a;
  rk_2 <- b;
  # Recurrence Formula:  r_k =  r_k-1 modulo r_k-2
  # Increment k until r_k-2 == 0
  while(rk_2 != 0) {
    rk      <- rk_1%%rk_2; # remainder
    rk_1    <- rk_2;       # proceed in recurrence
    rk_2    <- rk;
  }
  return(rk_1)
}