[r6rs-discuss] Confusion over |p

From: Alan Watson <alan>
Date: Wed, 27 Jun 2007 17:03:02 -0500

Supposed an implementation uses IEEE double-precision numbers for all
inexact reals. What should the implementation do when presented with
1.1|24? I can think of at least three reasonable options:

(a) Find the IEEE double-precision number that is closest to 1.1. That
is, treat it as 1.1|53.

(b) Find the binary floating-point number with 24 bits of precision that
is closest to 1.1 and represent this as an IEEE double-precision number.
That is, perform a correctly-rounded conversion to 24-bits of precision.

(c) Find the IEEE double-precision number that is closest to 1.1, round
the result to 24 bits of precision, and represent the result as an IEEE
double-precision number. That is, potentially, perform double rounding.

Does the draft R6RS require or forbid any of these options?

Regards,

Alan
Received on Wed Jun 27 2007 - 18:03:02 UTC