R

Question

我试图用R编写牛顿·拉普森程序：

mle_estimate <- function(x,start, eps, t_i_begin, error_begin){

      t0 <- start  
      t_i_next <- t_i_begin
      error <- error_begin
      while (error >= eps) {


      t_i_next <- t0 - first_partial(x, t0)/second_partial(x, t0)

      error <- abs(t_i_next - t0)  

      t0 <- t_i_next


      }

      return (t_i_next)
}

但是，当我使用以下程序测试程序时：

x <- c(1.77, -0.23, 2.76, 3.8, 3.47, 56.75, -1.34,
4.24, -2.44, 3.29, 3.71, -2.4, 4.53, -0.07, -1.05,
-13.87, -2.53, -1.75, 0.27, 43.21) 

mle_estimate(x, 10, 5, 3, 12)

我收到了以下警告 警告消息：

1: In while (error >= eps) { ... :
  the condition has length > 1 and only the first element will be used
2: In while (error >= eps) { ... :
  the condition has length > 1 and only the first element will be used
3: In while (error >= eps) { ... :
  the condition has length > 1 and only the first element will be used
4: In while (error >= eps) { ... :
  the condition has length > 1 and only the first element will be used

有人知道为什么“条件长度> 1 ...”的消息吗？因为我在while循环中的情况似乎只是变量“ error”和“ eps”的当前值的比较？

编辑：这是我的偏导数：

first_partial <- function(x, theta_current){
  fp <- 0
  fp <- sum((2*(x-theta_current))/((x-theta_current)^2 + 1))
  return (fp)
}

second_partial <- function(x, theta_current){
  sp <- 0
  sp <- (-2*(x-theta_current)*((x-theta_current)^2+1) + 4*(x-theta_current)*(x-theta_current))/(((x-theta_current)^2 + 1)^2)

}