Hi,

In message "Re: Math errors"
    on Fri, 18 Dec 2009 17:30:15 +0900, "W. James" <w_a_x_man / yahoo.com> writes:

|irb(main):007:0> -27 ** (1/3.0)
|=> -3.0

It's -(27 ** (1/3.0)).

							matz.