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Re: reading NaNs
| From: "Marcin 'Qrczak' Kowalczyk" <qrczak@xxxxxxxxxx>
| Date: Mon, 24 Oct 2005 20:17:43 +0200
| Aubrey Jaffer <agj@xxxxxxxxxxxx> writes:
| > We worked through this issue in SRFI-70. I think SRFI-70's
| > treatment is Schemely, compatible with IEEE-754, and doesn't
| > unnecessarily constrain implementations:
| > The notation 0/0 is used within this report to designate a
| > numerical error-object. A numerical function may return such
| > an object when no other number (including real infinities) is
| > the correct value. An implementation may report a violation of
| > an implementation restriction in any calculation for which the
| > result would be 0/0.
| It's not compatible with IEEE-754 because it doesn't guarantee that
| by default operations like (/ 0.0 0.0) produce NaN.
Aren't there IEEE-754 modes which throw an exception rather than
If the hardware returns a NaN, what the Scheme implementation does
with the NaN is not within the scope of IEEE-754.