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From: Ada novice <ycalleecharan@gmx.com>
Newsgroups: comp.lang.ada
Subject: Re: understanding floating point types
Date: Sun, 22 Aug 2010 10:15:24 -0700 (PDT)
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On Aug 22, 3:57=A0pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
>
> =A0 =A0My_Float'Machine_Mantissa =3D 53 (64-bit IEEE 754 is used to model=
 it)
> =A0 =A0My_Float'Mantissa =3D 25
>

Yes. This is good. For Long_Float, Long_Float'Mantissa is 51.


>
> I would expect that all computations performed in machine numbers, not
> because it is mandated, I believe it is not, but because it is simpler to
> implement. At least with GNAT it is so. Try this:
>
> =A0 =A0type My_Float is digits 2;
> =A0 =A0X : My_Float :=3D 1.0 / 3.0;
> =A0 =A0...
> =A0 =A0Put_Line (Float'Image (Float (X)));
>
> The output will be: 3.33333E-01
>
> If you can pick any number from the interval [0.33, 0.34[ to represent 1/=
3
> in with 2 decimal digits. Why not 0.333333?
>

I didn't quite get this part. In my previous example with say a =3D 2.33
and b =3D 3.45. Does Multiplication of a with b mean converting each of
a and b in model number first and then do the multiplication and
afterwards approximating the result to the nearest model number? Or
the multiplication will just be performed with the two numbers as 2.33
X 3.45 =3D 8.0385 and then approximating this result to the nearest
model number?

Thanks.

YC