From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Subject: Re: Question about ordinary fixed point types.
Date: Tue, 17 Aug 2010 17:51:38 +0200
Date: 2010-08-17T17:51:38+02:00 [thread overview]
Message-ID: <87wrrputit.fsf@ludovic-brenta.org> (raw)
In-Reply-To: 91d38fa6-4782-4e39-8df5-c4ba6d3a4ec7@d8g2000yqf.googlegroups.com
sjw writes on comp.lang.ada:
> On Aug 16, 11:03 am, Ludovic Brenta <ludo...@ludovic-brenta.org>
> wrote:
>
>> However and unfortunately, ARM 3.5.9(21) allows an implementation to
>> reject any 'Small that is not a power of two (and, in particular,
>> decimal fixed-point types). I'm not sure whether GNAT supports
>> arbitrary Smalls; from the doc, it seems that it actually rounds them
>> down to a power of two no smaller than 2**(-63).
>
> 2**(-63)! That should be OK in this application, then.
Yes but I suspect it requires 64-bit hardware. I don't think this would
work on a 16-bit microcontroller.
> The real question for Peter is, what does his target compiler do? If
> it does as GNAT does and allows a delta and matching small of
> ada.numerics.pi / 2 ** 15 then it makes sense to work in your scheme,
> since literal values in the code and values for debug will be in
> radians. If it only alows binary smalls, then (I would) work with
> delta 2 ** (-15) range -1.0 .. 1.0, ie signed fractions of pi, and
> apply the scaling factor as required.
Right.
--
Ludovic Brenta.
next prev parent reply other threads:[~2010-08-17 15:51 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-15 21:43 Question about ordinary fixed point types Peter C. Chapin
2010-08-15 21:55 ` Shark8
2010-08-16 0:46 ` Peter C. Chapin
2010-08-16 4:13 ` Jeffrey Carter
2010-08-16 8:57 ` Simon Wright
2010-08-15 22:08 ` Yannick Duchêne (Hibou57)
2010-08-16 1:03 ` Peter C. Chapin
2010-08-16 4:11 ` Jeffrey Carter
2010-08-16 10:03 ` Ludovic Brenta
2010-08-17 14:35 ` sjw
2010-08-17 15:51 ` Ludovic Brenta [this message]
2010-08-16 11:31 ` Peter C. Chapin
2010-08-16 9:23 ` Simon Wright
2010-08-16 15:47 ` Simon Wright
2010-08-17 14:37 ` sjw
2010-08-16 11:02 ` Stephen Leake
2010-08-16 11:29 ` Peter C. Chapin
2010-08-16 12:53 ` Dmitry A. Kazakov
2010-08-16 20:28 ` Peter C. Chapin
2010-08-16 20:58 ` Adam Beneschan
2010-08-16 13:01 ` Dmitry A. Kazakov
2010-08-16 14:28 ` Robert A Duff
2010-08-16 20:31 ` Peter C. Chapin
2010-08-16 23:01 ` Robert A Duff
2010-08-16 23:17 ` Peter C. Chapin
2010-08-17 0:56 ` Robert A Duff
2010-08-17 2:03 ` Stephen Leake
2010-08-20 1:21 ` Yannick Duchêne (Hibou57)
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