Re: Newbie Q

["Dr. Adrian Wrigley" <amtw@linuxchip.demon.co.uk.uk.uk>]

On Tue, 20 Sep 2005 04:09:26 +0000, Jim Rogers wrote:
> The example does not indicate whether Degrees is a fixed point or
> floating point type. This example would work better with a fixed
> point type than with a floating point type because one can always
> know what the minimum delta between two fixed point numbers is.

The minimum step is known as the *small* of the type (RM 3.5.9:8).
The *maximum* smallest step is given by the "delta" of the type,
but implementations are free to choose smaller steps unless an
attribute is applied specifying the "small".

I'm sure you know this, but I had only realized this a few weeks ago
when talking about wanting to address arrays by fixed point types.

I had got the impression that all fixed point values were integer
multiples of the delta, whereas in fact there may be additional
bits of precision used by the type.  This seemed counter-intuitive.

(what is the rationale for delta /= small?)
-- 
Adrian