On Tue, 30 Jan 2007, Jan Engelhardt wrote:
>
> >> Why the qualifier? Zero *is* not a power of 2, is it?
>
> No, it is not:
>
> In[1]:= Solve[2^n == 0, n]
>
> Out[1]= {}
>
> So says Mathematica5.
oooookay, that's kind of like taking a sandblaster to a soup cracker.
seriously, though, there is the potential of breaking something with
this change since you can see how there is some inconsistency in how
it's done *now* just for powerpc which, in some places, defines its
own versions of this:
./arch/ppc/mm/pgtable.c:
#define is_power_of_2(x) ((x) != 0 && (((x) & ((x) - 1)) == 0))
./arch/ppc/syslib/ppc85xx_rio.c:
#define is_power_of_2(x) (((x) & ((x) - 1)) == 0)
./arch/powerpc/mm/pgtable_32.c:
#define is_power_of_2(x) ((x) != 0 && (((x) & ((x) - 1)) == 0))
note how the first and third macros *won't* consider zero a power of
two, while the second one *will*. hence the need for a single
standard for all of this, just to play it safe.
rday
p.s. in case you missed it, that was a not-so-subtle plea to please
just apply this patch so we can move on.
--
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA
http://www.fsdev.dreamhosters.com/wiki/index.php?title=Main_Page
========================================================================
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