R语言 代码解释及验证

 Following is a recursive function which takes as input (argument) a vector $x$ and returns a scalar. Either by looking carefully at the function, or by running the function with a few simple input vectors and observing the returned values in each case, determine what the function is doing.

```{r}
myfun  <- function(x) {
  if (length(x) == 1) {
    return(x)
  } else
    return(x[1] + myfun(x[-1]))
}
myfun(c(1:1000)) #here's what happens when it is applied to 1:1000

Describe in precise words what the function does 

ANSWER:

- Modify the function slightly so that it returns the value:

$\sum_{i=1}^n e^{x_i}$ 

In other words, we want to write a function that calculates the sum of the exponential of each component of the input vector $x$.

Test your function with the argument vector: `x <- c(2,1,3,0.4)`. You should get an answer approximately equal to 31.6847 .

# add your own R code below this line

```

基于Monster 组和GPT的调写：

• 给定的递归函数 myfun() 接受一个向量 x 作为输入，并递归求和其元素。它首先检查向量的长度是否为1，如果是，则返回向量的唯一元素。如果向量的长度大于1，则返回向量第一个元素与 myfun() 函数递归应用于除第一个元素外的其余部分的结果之和。

为了返回每个组件的指数之和，可以将函数 myfun() 修改如下：

myfun <- function(x) {
  if (length(x) == 1) {
    return(exp(x))
  } else {
    return(exp(x[1]) + myfun(x[-1]))
  }
}

用输入向量 x <- c(2, 1, 3, 0.4) 来测试函数，我们应该得到一个大约等于 31.6847 的答案。

x <- c(2, 1, 3, 0.4)
sum_of_exp_x <- myfun(x)
print(sum_of_exp_x)