Re: Simple Real_Time.Time_Span question

[Keith Thompson <kst@cts.com>]

eachus@spectre.mitre.org (Robert I. Eachus) writes:
> In article <700ic6$q1p$1@nnrp1.dejanews.com> dennison@telepath.com writes:
>    1) You've got to be kidding!  Converting time to floating point to
> do calculations is what caused problems with the Patriot system in
> Dahran.

A brief summary: floating-point is tricky.

>    2) Any fixed point value can be converted to any floating point
> type.  The precision and accuracy will be determined by the types
> involved.  You seem to be under the impression that (double-precision)
> floating point will be more accurate than Duration.  Assuming that
> Duration is a 64-bit fixed point type (and the annexes encourage such
> an implementation), this will usually not be the case.

But you can't assume this in portable code.  I'm reasonably certain
that there are existing Ada 95 implementations in which Duration is 32
bits -- and the original poster explicitly said that the code would
have to be ported to other implementations.

-- 
Keith Thompson (The_Other_Keith) kst@cts.com <http://www.ghoti.net/~kst> <*>
Qualcomm, San Diego, California, USA  <http://www.qualcomm.com>
I must be a techno-geek.  My mouse is bigger than my phone.