[r6rs-discuss] put-datum, get-datum, equal?, eqv?, and NaNs

From: Alan Watson <alan>
Date: Sat, 30 Jun 2007 18:54:21 -0500

William D Clinger wrote:
>>> Or the rule that says a
>>> denormalized double precision number really ought to
>>> be printed with an explicit mantissa width?
>> Where does it say that?
>
> This note in section 4.2.8 of the R5.96RS draft:
>
> Note: When the underlying floating-point
> representation is IEEE double precision, the |p
> suffix should not always be omitted: Denormalized
> floating-point representations have diminished
> precision, and therefore their external
> representation should carry a |p suffix with the
> actual width of the significand.
>
> Fortunately, that is only a "should".

I believe this means "the programmer should write subnormals in their
program and in data using explicit precisions" not "number->string and
its friends should by default add an appropriate |p to subnormals".

This requirement on the programmer (along with the effective promotion
of 1.1f0 to 1.1f0|53) strikes me as unreasonable and unjustified.

Regards,

Alan
Received on Sat Jun 30 2007 - 19:54:21 UTC