In article <3CB8A47F.40E4D194@gmx.de> , Christoph Hormann 
<chr### [at] gmxde>  wrote:

> Results
> with negative base and non integer exponent are not defined, i suppose you
> would have to catch this case inside Povray to make sure to get identical
> results in all versions.

No, it cannot efficiently without needless penalty for all platforms.  The
error is in the Visual C library because (even the ancient 1989 version of)
the C standard specifies pow to return NaN* in this case and to (optionally)
issue an exception/signal.  Unfortunately the Visual C library apparently
fails to do either :-(


    Thorsten


* Actually, it says this will only be the case if the implementation also
complies to IEC 60559:1989 which is basically IEEE 754-1985, aka "THE
floating-point number standard".  Intel FPUs comply to this standard like all
processors available today, so the compiler is outdated or intentionally
breaking the standard to preserve some backward compatibility as M$ usually
calls these bugs :-(

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

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