用r语言编写一个函数，返回一个向量的偏度skewness和峰度kuetosis函数

skewness <- function(x){
n <- length(x)
mean_x <- mean(x)
sd_x <- sd(x)
skewness <- sum((x-mean_x)^3)/(n*(sd_x^3))
return(skewness)
}

kurtosis <- function(x){
n <- length(x)
mean_x <- mean(x)
sd_x <- sd(x)
kurtosis <- sum((x-mean_x)^4)/(n*(sd_x^4)) - 3
return(kurtosis)
}

# 测试
x <- c(1,2,3,4,5)
skewness(x)
kurtosis(x)