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Re: arithmetic issues

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.

Aubrey Jaffer scripsit:

> For an interpreter this would mean that 1/2 read before the full-tower
> module was loaded could be an inexact 0.5; but after loading 1/2 would
> read as an exact 1/2.  Unpredictability is bad.

It would merely mean that 1/2 would be an error (and preferably would
signal an error as well).  Of course, #e1/2 would still be an inexact 0.5.

> I recommend 12.bits minimum precision for both fixnums and flonums.

I think that's way too small, particularly if we are going to explicitly
adopt CL's link between fixnums and {string,vector} indices.

> Both Common-Lisp and SLIB implement MOST-POSITIVE-FIXNUM and
> MOST-NEGATIVE-FIXNUM, which would be good additions to R6RS.


> Its time to move beyond the machine-language mindset.  I code in
> Scheme because I want a high-level language.

Agreed.  I've been pointing out in #scheme that the Lisp/Scheme community,
like the Fortran and ML communities (and unlike assembler, Perl, Python,
and Haskell communities), suffered a psychological wound in the early
days of the form "Your language is too slow, therefore you suck" that has
left it with an obsession with speed, speed, speed.

> Being error objects, syntax for NaNs should be unspecified.

I don't see how that follows.

> None of the examples in SRFI-77 return -0.0 unless they are passed
> -0.0 as an argument.  Does -0.0 result only from a literal -0.0
> constant?
> In an implementation with -0.0, what is the result of (* -5.0 0.0)?
> -0.0 is insufficiently specified by SRFI-77; it will be a portability
> killer.

The IEEE standard is our friend here.

Said Agatha Christie / To E. Philips Oppenheim  John Cowan
"Who is this Hemingway? / Who is this Proust?   jcowan@xxxxxxxxxxxxxxxxx
Who is this Vladimir / Whatchamacallum,         http://www.reutershealth.com
This neopostrealist / Rabble?" she groused.     http://www.ccil.org/cowan
        --author unknown to me; any suggestions?