* Complex, exact numbers
@ 2010-09-26 22:00 Mike Gran
2010-09-27 20:27 ` Andy Wingo
2010-09-27 21:02 ` Neil Jerram
0 siblings, 2 replies; 4+ messages in thread
From: Mike Gran @ 2010-09-26 22:00 UTC (permalink / raw)
To: guile-devel
Hi all-
Should a number be able to be both complex and exact?
The R6RS isn't helpful in answering this question. It says
"A number object is exact if it is the value of an exact
numerical literal or was derived from exact number objects
using only exact operations. Exact number objects correspond
to mathematical numbers in the obvious way."
$ meta/guile -c "(write 0+i) (newline)"
> 0.0+1.0i
$ meta/guile -c "(write #e0+i) (newline)"
> ERROR: In procedure inexact->exact:
> ERROR: Wrong type argument in position 1: 0.0+1.0i
Thanks,
Mike
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Complex, exact numbers
2010-09-26 22:00 Complex, exact numbers Mike Gran
@ 2010-09-27 20:27 ` Andy Wingo
2010-09-27 20:47 ` Mike Gran
2010-09-27 21:02 ` Neil Jerram
1 sibling, 1 reply; 4+ messages in thread
From: Andy Wingo @ 2010-09-27 20:27 UTC (permalink / raw)
To: Mike Gran; +Cc: guile-devel
On Mon 27 Sep 2010 00:00, Mike Gran <spk121@yahoo.com> writes:
> Should a number be able to be both complex and exact?
It can be in theory. However in Guile complex numbers are always
inexact.
Do you need exact complex numbers? It's probably possible to
implement, but I don't know of any use for them.
Andy
--
http://wingolog.org/
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Complex, exact numbers
2010-09-27 20:27 ` Andy Wingo
@ 2010-09-27 20:47 ` Mike Gran
0 siblings, 0 replies; 4+ messages in thread
From: Mike Gran @ 2010-09-27 20:47 UTC (permalink / raw)
To: Andy Wingo; +Cc: guile-devel
> From: Andy Wingo <wingo@pobox.com>
> On Mon 27 Sep 2010 00:00, Mike Gran <spk121@yahoo.com> writes:
>
> > Should a number be able to be both complex and exact?
>
> It can be in theory. However in Guile complex numbers are always
> inexact.
>
> Do you need exact complex numbers? It's probably possible to
> implement, but I don't know of any use for them.
>
I don't need them. I was just curious.
I updated a script I had to try to exercise all possible
number, character, identifier and string branches in a R6RS parser.
I used it to examine the parsing differences between Guile-1.8.x,
Guile-1.9.x, and MzScheme, which was rather amusing. The exact,
complex number is partially implemented by MzScheme.
Thanks,
Mike
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Complex, exact numbers
2010-09-26 22:00 Complex, exact numbers Mike Gran
2010-09-27 20:27 ` Andy Wingo
@ 2010-09-27 21:02 ` Neil Jerram
1 sibling, 0 replies; 4+ messages in thread
From: Neil Jerram @ 2010-09-27 21:02 UTC (permalink / raw)
To: Mike Gran; +Cc: guile-devel
Mike Gran <spk121@yahoo.com> writes:
> Hi all-
>
> Should a number be able to be both complex and exact?
Mathematically, I'd say yes.
To argue against, you'd have to argue that i is (for some reason)
inexact, and I can't see any reason for that.
Neil
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-09-26 22:00 Complex, exact numbers Mike Gran
2010-09-27 20:27 ` Andy Wingo
2010-09-27 20:47 ` Mike Gran
2010-09-27 21:02 ` Neil Jerram
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