Embarrassed to ask

[jebem]

(07-16-2014 08:38 PM)Mark Hardman Wrote:  

(07-16-2014 07:48 PM)jebem Wrote:  Interesting... and my HP-15C gives me an Domain Error.
I mean, using -8^( 2/3)

Try setting the 15C to complex mode (g SF 8).

Yes, the HP-15C answer is a complex number:
-2.0000 for real and 3,4641 for imaginary part.
where 3,4641 should be the approximation for 2*sqrt(3)

and of course my HP-42S doesn't even need to be told to enter complex mode, as it just gave a straight answer in the x stack register:
x: -2.0000 i3.4641

And just for the record, a HP-27S answer for -8^( 2/3) is:
ERROR: NEG^NONINTEGER

And Google itself is answering like this:
(-8)^(2 / 3) =
-2 + 3,46410162 i