Re: __builtin_cpow((0,0),(0,0))

[Ronny Peine <RonnyPeine at gmx dot de>]

Dave Korn wrote:
> ----Original Message----
>
> > From: Ronny Peine
> > Sent: 16 March 2005 17:34
>
>
> > See for example:
> > http://mathworld.wolfram.com/ExponentLaws.html
>
>
>   Ok, I did.
>
>
> > Even though, gcc returns 1 for pow(0.0,0.0) in version 3.4.3 like many 
> > other c-compiler do. The same behaviour would be expected from cpow.
>
>
>   No, you're wrong (that the same behaviour would be expected from cpow).
> See for example:
>
> http://mathworld.wolfram.com/ExponentLaws.html
>
> " Note that these rules apply in general only to real quantities, and can
> give manifestly wrong results if they are blindly applied to complex
> quantities. "
>
> <g>

Well yes in the general case it's not applieable, but x^0 is 1 in the 
complex case, too. And if 0^0 is converted from the real to the complex 
domain (it's even a part of the complex domain) than the same behaviour 
would be expected, otherwise the definition wouldn't be very well.

Has anyone found a hint in the ieee754 standard if there is something 
about it in there? I haven't one here right now, well it's not 
prizeless. Otherwise these discussion won't end.

>     cheers,
>       DaveK

cu, Ronny