Decimal floating point on x86 and ARM?

By: rwessel (rwessel.delete@this.yahoo.com), December 19, 2020 8:54 am
Room: Moderated Discussions
dmcq (dmcq.delete@this.fano.co.uk) on December 19, 2020 3:41 am wrote:
> rwessel (rwessel.delete@this.yahoo.com) on December 18, 2020 6:57 pm wrote:
> > anon (an.delete@this.n.com) on December 18, 2020 8:29 am wrote:
> > > I read that C2X (the next C language revision) will add support for decimal floating point.
> > > I know that POWER and SPARC CPUs have hardware support for decimal FP,
> > > but are there any plans to include it on future x86 or ARM CPUs?
> > >
> > > Also, which languages have native support (without libraries) for decimal FP right now?
> > > I know of COBOL, PL/I, Ada, C# and F#. Any others?
> >
> >
> > The ("floating") decimal type in C# and F# bear no resemblance
> > to the IEEE decimal format, and little to anything
> > we'd normally consider an FP format. The .NET format is
> > a 96 bit binary integer with a decimal scale (10**0
> > to 10**-28). Useful for currency, to be sure, but not meaningfully related to IEEE decimal FP.
>
> Oracle's number format is base 100 and adjusted so comparisons work easily as strings. It does have an exponent,
> but yep, oveall no resemblance. And databases are an especially important place for decimal numbers.


As I've frequently* pointed out, there's not actually any need for decimal numbers, but decimal scaling *is* important. For something like a database column, that scaling factor is probably best stored in the attributes for the column. (at least for most purposes). For computational purposes it makes sense to store the scale explicitly, but for a storage format you'd generally want to normalize** the number first.


*Not to worry, it's a bit of a hobbyhorse for me.

**Not quite the same definition as for FP, but scaling and rounding so that the (computational) scale factor (exponent) is the same as that of the storage format.
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TopicPosted ByDate
Decimal floating point on x86 and ARM?anon2020/12/18 09:29 AM
  Decimal floating point on x86 and ARM?Per Hesselgren2020/12/18 10:16 AM
    Decimal floating point on x86 and ARM?anon2020/12/18 12:23 PM
      Decimal floating point on x86 and ARM?dmcq2020/12/18 06:18 PM
  Decimal floating point on x86 and ARM?rwessel2020/12/18 07:57 PM
    Decimal floating point on x86 and ARM?dmcq2020/12/19 04:41 AM
      Decimal floating point on x86 and ARM?rwessel2020/12/19 08:54 AM
        Decimal floating point on x86 and ARM?Michael S2020/12/19 10:48 AM
          Decimal floating point on x86 and ARM?rwessel2020/12/20 09:25 AM
            Decimal floating point on x86 and ARM?blaine2020/12/20 11:52 AM
              Decimal floating point on x86 and ARM?rwessel2020/12/20 01:44 PM
                Decimal floating point on x86 and ARM?blaine2020/12/20 05:29 PM
              Decimal floating point on x86 and ARM?Konrad Schwarz2020/12/21 04:17 AM
            Decimal floating point on x86 and ARM?Adrian2020/12/21 10:05 AM
  Decimal floating point on x86 and ARM?Konrad Schwarz2020/12/20 09:47 AM
    Decimal floating point on x86 and ARM?rwessel2020/12/20 11:28 AM
    Decimal floating point on x86 and ARM?Linus Torvalds2020/12/20 11:39 AM
      Decimal floating point on x86 and ARM?dmcq2020/12/20 12:06 PM
        Decimal floating point on x86 and ARM?Konrad Schwarz2020/12/21 03:31 AM
          Decimal floating point on x86 and ARM?Brendan2020/12/21 05:49 AM
            Decimal floating point on x86 and ARM?dmcq2020/12/21 07:59 AM
      Decimal floating point on x86 and ARM?Adrian2020/12/21 09:51 AM
        Decimal floating point on x86 and ARM?Linus Torvalds2020/12/21 12:12 PM
          Decimal floating point on x86 and ARM?Adrian2020/12/21 01:29 PM
          Decimal floating point on x86 and ARM?dmcq2020/12/21 04:13 PM
      Decimal floating point on x86 and ARM?David Hess2020/12/21 07:15 PM
        Decimal floating point on x86 and ARM?Konrad Schwarz2020/12/22 01:04 AM
          Decimal floating point on x86 and ARM?David Hess2020/12/22 01:05 PM
    Decimal floating point on x86 and ARM?blaine2020/12/20 12:40 PM
      Decimal floating point on x86 and ARM?Per Hesselgren2020/12/21 04:33 AM
        Decimal floating point on x86 and ARM?rwessel2020/12/21 06:17 AM
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