# Re: Wrapping up SRFI-70

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``` | Date: Mon, 15 Aug 2005 09:38:34 -0700
| From: Per Bothner <per@xxxxxxxxxxx>
|
| Aubrey Jaffer wrote:
| > I believe that the junking of 0/0 makes SRFI-70 compatible with
| > IEEE-754.  Do you agree?
|
| It's a bit awkward.  The syntax 0/0 suggests 0/0 is exact.
| The 0/0 syntax is extra awkward for an implementation that
| defines 1/0 and -1/0 as exact infinities, as Kawa does.

SRFI-70 specifies no Scheme notation for 0/0.  It is used in the
Specification to stand for a numeric error-object (or violation of
implementation restriction).

| (Exact infinites are an experimental addition in Kawa  I won't claim
| they're terribly well-specified or justified.  I think they can be
| useful in some situation, such as sentinel values.)
|
| I did find some discrepencies between your specification and Kawa:
|
| #|kawa:21|# (define neg-inf (/ -1.0 0.0))
| #|kawa:22|# neg-inf
| #i-1/0
| #|kawa:23|# (log neg-inf)
| #i1/0+3.141592653589793i
| #|kawa:26|# (sqrt neg-inf)
| #i+1/0i
|
| Kawa allows complex numbers with infinite components.
| Whether this is "correct" or accidental I don't know.

Non-real numbers with infinite components would all be SRFI-70

| Also I got:
|
| #|kawa:30|# (angle neg-inf)
| 0

The result should be pi, the same as (angle -1).

| #|kawa:29|# (angle inf)
| 0

If inf is inexact, then (angle inf) should be 0.0

```