__builtin_cpow((0,0),(0,0))

[Ronny Peine]

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