[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

This page is part of the web mail archives of SRFI 77 from before July 7th, 2015. The new archives for SRFI 77 contain all messages, not just those from before July 7th, 2015.

*To*: srfi-77@xxxxxxxxxxxxxxxxx*Subject*: Re: +nan.0 problems*From*: Marcin 'Qrczak' Kowalczyk <qrczak@xxxxxxxxxx>*Date*: Sat, 22 Oct 2005 20:52:50 +0200*Delivered-to*: srfi-77@xxxxxxxxxxxxxxxxx*In-reply-to*: <20051022163037.D2AFB1B77BB@xxxxxxxxxxxxxxxxxxxxx> (Aubrey Jaffer's message of "Sat, 22 Oct 2005 12:30:37 -0400 (EDT)")*Mail-followup-to*: srfi-77@xxxxxxxxxxxxxxxxx*References*: <20051021145326.816C11B77BB@xxxxxxxxxxxxxxxxxxxxx> <20051021155906.GC16464@NYCMJCOWA2> <Pine.LNX.4.58.0510210910130.18969@xxxxxxxxxxxxxx> <20051022020312.GB5632@NYCMJCOWA2> <20051022163037.D2AFB1B77BB@xxxxxxxxxxxxxxxxxxxxx>*Sender*: Marcin 'Qrczak' Kowalczyk <qrczak@xxxxxxxxxx>*User-agent*: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux)

Aubrey Jaffer <agj@xxxxxxxxxxxx> writes: > The total order of the reals is a crucial property for many > applications. It is well known that the default order on the floating point approximation of reals is not total. Not that it's the only pitfall. Some applications might rely on the fact that x + y - x = y, which is false in this world too. But at least all languages providing an interface to IEEE floats have the same pitfalls. IEEE anticipates the possibility of letting various errors be signalled (in a catchable way) instead of producing special answers. It would be a challenge to make this accessible from Scheme. C99 allows to track this as changing a global set of flags; on Unix it can generate a SIGFPE signal. I'm not familiar with details. I've heard that CMUCL and SBCL deal with this (through the Unix way). > This could be resolved by either: > > (real? +nan.0) ==> #f and (complex? +nan.0) ==> #f > > or > > Stop using the term `real' to refer to IEEE flonums. How about > RIEEEL? If +nan.0 is not considered real nor complex, beware that some operations which used to be treated as closed over these fields are no longer closed. I'm not sure which is worse. I like the name RIEEEL :-) -- __("< Marcin Kowalczyk \__/ qrczak@xxxxxxxxxx ^^ http://qrnik.knm.org.pl/~qrczak/

**Follow-Ups**:**Re: +nan.0 problems***From:*Thomas Bushnell BSG

**Re: +nan.0 problems***From:*Aubrey Jaffer

**References**:**arithmetic issues***From:*Aubrey Jaffer

**Re: arithmetic issues***From:*John.Cowan

**Re: arithmetic issues***From:*bear

**Re: arithmetic issues***From:*John.Cowan

**+nan.0 problems***From:*Aubrey Jaffer

- Prev by Date:
**multiplicative inverse of 0.0** - Next by Date:
**Re: Exactness** - Previous by thread:
**+nan.0 problems** - Next by thread:
**Re: +nan.0 problems** - Index(es):