[英]Recursive function in R of a sequence
I am trying to write a function that takes X and n, and returns element Xn.我正在尝试编写一个采用 X 和 n 并返回元素 Xn 的 function。 X is a vector of the first 3 elements of the sequence and n is a positive integer.
X 是序列的前 3 个元素的向量,n 是正 integer。 Xn = Xn-1 + Xn-2 - Xn-3
Xn = Xn-1 + Xn-2 - Xn-3
I am not sure how to outline a function like this in R.我不确定如何在 R 中像这样概述 function。 Can someone outline the creation of a recursive function for the above numerical sequence?
有人可以概述为上述数字序列创建递归 function 吗?
I have been working with something like this:我一直在处理这样的事情:
myfunc <- function(x,n){
if (n<0){
print("please enter positive integer")
} else {
return(myfunc(n-1 + n-2 + n-3))
}
}
myfunc (x = c(1, 2, 3), n = 3) #should return 3 (third number in sequence)
myfunc (x = c(1, 2, 3), n = 4) #should return 6
This isn't a recursive function, but it will give you what you want:这不是递归 function,但它会给你你想要的:
myfunc <- function(x, n) sum(x[n - 1:n])
myfunc(1:3, 3) # 3
myfunc(1:3, 4) # 6
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