r - Real cube root of a negative number

Question

I'm trying to see if there is a function to directly get the real cube root of a negative number. For example, in Java, there is the Math.cbrt() function. I'm looking for the equivalent in R.

Otherwise, my current hack is:

x <- -8
sign(x) * abs(x)^(1/3)

which is very inelegant and cumbersome to type every time. Thx!

Answer 1

Sounds like you just need to define your own Math.cbrt() function.

That will turn performing the operation from something inelegant and cumbersome to something clean, expressive, and easy to apply:

Math.cbrt <- function(x) {
    sign(x) * abs(x)^(1/3)
}

x <- c(-1, -8, -27, -64)

Math.cbrt(x)
# [1] -1 -2 -3 -4