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Date: Wed, 22 Jan 2014 18:53:29 +0100
From: "G.B." <rm-dash-bau-haus@dash.futureapps.de>
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Subject: Re: How to round to the nearest fixed-point value?
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Date: 2014-01-22T18:53:11+01:00
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On 22.01.14 17:48, Natasha Kerensikova wrote:
>     function Convert (Value : High) return Low is
>     begin
>        return Low'Round (Value);
>     end Convert;

In view of LRM 4.6, Numeric Type Conversion,
I speculate that the compiler might be right. If only I knew
how truncation might play a role(+):

      * If the target type is a decimal fixed point type, then
        the result is truncated (toward 0) if the value of the
        operand is not a multiple of the small of the target
        type.

Then, rewriting,

    function Convert (Value : High) return Low is
       Result : constant High := High'Round (Value);
    begin
       return Low (Result);
    end Convert;

Result has 0.999 exactly if this is a multiple of High'Small
(it is, with GNAT on Intel), but converting to Low truncates
because Low'Small is too big by a factor of 10.

__
(+) Low'Round takes a universal_real (and returns Low'Base); does
universality affect things?