real_return_n.R

#' Calculate the real return on an index fund.
#'
#' @param yield - percent as a decimal
#' @param expense_ratio - percent as a decimal
#' @param balance 
#' @param n - number of years
#'
#' @return
#' @examples
real_return_n <- function(yield, expense_ratio, starting_balance, n) {
  return_n <- starting_balance
  sapply(
    1:n, 
    function(i) {
      return_n <<- real_return(yield, expense_ratio, return_n)
    })
  return_n
}