$ perl -le'print -3 ** (1/3)'
-1.44224957030741

##</code><code>##

>perl -le"print -3 ** (1/3)"
-1.44224957030741

##</code><code>##

$ perl -le'print( (-3) ** (1/3) )'
nan

##</code><code>##

>perl -e"print( (-3) ** (1/3) )"
-1.#IND