Re: Integers and Mathematical Correctness

["chris.danx" <chris.danx@ntlworld.com>]

> "chris.danx" wrote:
> > To most this may seem insignificant but I'm more mathematically minded
and I
> > just found something out.  Many programming languages don't implement
> > division properly!
>
> In the case of Ada, "properly" means
>
>    (-A)/B = -(A/b) = A/(-B)     RM95 4.5.5(6-7)
>
> See also the notes on the next page (para. 23-30).
> If the compiler doesn't do this, send a bug report.
>
> If your c_integer package is going to do something
> else, I would advise the following comment at the
> beginning of it:
>
> -- NOTE: This package redefines integer division
> --       for the benefit of folks who think the
> --       RM definition is stupid.  Do not expect
> --       division of these types to behave like
> --       other integer types!

When did I say it was stupid?  I said it's technically incorrect, not that
it's stupid.  Division is performed this way in Ada because ppl expect it to
be.  They are taught it wrongly, they are taught that negative remainders
are allowed which changes the whole division.

It is not stupid because ppl expect it to be this way, but it is technically
mathematically incorrect.


Chris