Re: [office-formula] BITAND, etc. - what about bitlimits/sign bit? Gnumeric folks, willing to change what they do?

["Andreas J. Guelzow" <aguelzow@math.concordia.ab.ca>]

On Fri, 2006-01-09 at 12:20 -0400, David A. Wheeler wrote:
> Andreas J. Guelzow wrote:
> > What does MS Excel do?
> >   
> Excel has no ability to perform bit operations at all, amazingly enough.
> This is one of its glaring weaknesses.  There are few that have bit 
> operations
> (Quattro Pro does).

I was asking that question because typically strange behaviour in
Gnumeric has as a reason that MS Excel does it that way.
> 
> Jody, Andreas: Any idea why it's limited to 32 bits?  Does anyone
> DEPEND on that behavior?  Perhaps that's something that can be asked
> on a Gnumeric mailing list?  I'd like to NOT require this 32-bit limitation,
> if that is reasonable.

I think we should figure out a _good_ specification with less concern
about what current applications implement. If gnumeric depends on its
current implementation, gnumeric would be free to add it as a gnumeric
specific function.

So more importantly, how do you envision a BITAND interface? Assuming
that we only allow integer arguments or truncate to integers what do we
do with negative numbers? For example if we require the specification of
a bit length as a third argument, Gnumeric could use its 2-argument
function as if it has an optional bit length argument defaulting to 32.

Let's write good definitions.

Andreas

> 
> Excel does have a few number conversion functions,
> like BIN2DEC.  In them, the topmost bit of the 10th largest digit
> of a non-base-10 number is considered the sign bit, and the entire
> value is considered two's complement.
> 
> Yes, it really is that weird.  No doubt to support all the
> 10-bit, 30-bit, and 40-bit systems that are on the market today :-).
> At least there are actual computers that use 32 bits.
> 
> --- David A. Wheeler
> 
-- 
Andreas J. Guelzow, Professor
Dept. of Mathematical & Computing Sciences
Concordia University College of Alberta