# recursion function r

```
r <- function(n) {
if (n <= 0) {
return(1)
} else {
return(n * r(n - 1))
}
}
```

Explanation:

- The function
`r`

is defined to take one parameter,`n`

. - Inside the function, there is an
`if`

statement to check if`n`

is less than or equal to 0. - If the condition is true, the function returns 1. This is the base case for the recursion.
- If the condition is false (i.e.,
`n`

is greater than 0), the function calculates the factorial of`n`

using recursion. - It calls itself with the argument
`n - 1`

and multiplies the result by`n`

. - The recursion continues until the base case is reached (when
`n`

becomes 0 or negative). - The final result is the product of all the numbers from
`n`

down to 1, which is the factorial of the original input`n`

.