Hi
I find that one often needs to keep reals real and complexes complex.
Try this:
"cuberooti" <-
function (x)
{
if (is.complex(x)) {
return(sqrt(x + (0+0i)))
}
sign(x)* abs(x)^(1/3)
}
best wishes
[see that (0+0i) sitting there!]
Robin
On 12 Jul 2005, at 14:11, [EMAIL PROTECTED]
wrote:
> hi all
>
> why does R do this:
>
> (-8)^(1/3)=NaN
>
> the answer should be : -2
>
> a silly question but i kept on getting errors in some of my code
> due to this
> problem.
>
> i solve the problem as follows:
>
> say we want : (-a)^(1/3)
>
> then : sign(a)*(a^(1/3)) works
>
> but there has to be a simpler way of soing such a simple
> mathematical operation.
>
> thanking you
> /
> allan
>
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--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
tel 023-8059-7743
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