I had my doubts and did some quick research

German Wikipedia states that it's disputed, if the cube root of a negative real number was defined.°

I couldn't find it in English sources in the hurry, but I suppose it's the old problem of having functions which fulfill certain qualities like reversibility in order to play well with the whole mathematical model.

In the end you'll have to handle two definitions of odd roots.

Hence your approach to define your own sub cube_root() looks fine for me. :)

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

°) https://de.wikipedia.org/wiki/Wurzel_(Mathematik)#Wurzeln_aus_negativen_Zahlen

update

Here the google translate for the laziest of lazy ...

In reply to Re: How to get better exponentiation? (undefined) by LanX
in thread How to get better exponentiation? by Athanasius

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