Re: How to round to the nearest fixed-point value?

[adambeneschan@gmail.com]

On Wednesday, January 22, 2014 9:53:29 AM UTC-8, G.B. wrote:
> 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;

This rewrite has nothing to do with the OP's code.  The OP's program does not perform High'Round anywhere, nor does it have any type conversions to which 4.6 would apply.

                               -- Adam


> 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.