[R6RS] Draft of arithmetic SRFI

[Michael Sperber]

I mostly did what you suggested.

New draft at:

http://www-pu.informatik.uni-tuebingen.de/users/sperber/srfi/arithmetic-srfi.html

I only had time to integrate this on autopilot, so I might have
misplaced some bits---I'll do a more thorough pass on the weekend.

Some remarks:

William D Clinger <will at ccs.neu.edu> writes:

> External Representations, fifth bullet:
> I'm not so sure about the x|53 interpretation because it discriminates
> against implementations that default to unusually good representations,
> such as IEEE extended precision.  Are there any such implementations?
> Do we expect such implementations in the near future?

I made that into an issue bullett.

> External Representations, second note:
> I don't know what the words "cannot" and "must" mean in this note.
> In this SRFI (as opposed to the 2004 paper by Egner et al), the
> <mantissa width> is used only for the external representation of
> inexact numbers, and the rule for interpreting those external
> representations allows implementations to use more or less precision
> than is called for by the <mantissa width>.  I'd recommend removal
> of the second note.

I still think it's important to say this---I've weakened the language.
 
> Lucier's Proposal:
> We probably ought to go back to Lucier's proposal and check the
> branch cuts, which I haven't done.  Maybe Mike did.

Well ...  Brad's proposal had this:

Brad> 13. atan, asin, acos, log, etc.
Brad> 
Brad> The complex functions with branch cuts should be changed to conform
Brad> to the following pages in the CL Hyperspec:
Brad> 
Brad> http://www.harlequin.com/education/books/HyperSpec/Body/fun_asincm_acoscm_atan.html
Brad> 
Brad> http://www.harlequin.com/education/books/HyperSpec/Issues/iss069-writeup.html
Brad> 
Brad> These changes conform to the interpretation given above of +0. and
Brad> -0. lying to the right and to the left of exact zero.

Except, AFAICS, R5RS already follows all of that so I have no idea
what Brad means when he says "change."  I'm sure he'll comment if I
screwed it up.  I'll try to remember querying him once the SRFI is
out.

-- 
Cheers =8-} Mike
Friede, V?lkerverst?ndigung und ?berhaupt blabla