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From: sjw <simon.j.wright@mac.com>
Newsgroups: comp.lang.ada
Subject: Re: Question about ordinary fixed point types.
Date: Tue, 17 Aug 2010 07:35:04 -0700 (PDT)
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Date: 2010-08-17T07:35:04-07:00
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On Aug 16, 11:03=A0am, 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.

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.