Decision, decisions. How /should/ you specify an extended infinity? I say
_x
|ill-formed number
There could be alternatives. _r(any finite) and (any non0)r0 are both
reasonable.
NOTE that the GMP library that we have moved to has no way to represent
extended infinity. Raul has chosen 1r0 as our internal representation
of extended infinity, so infinity will always have rational precision,
not extended integer.
For display, we get it right:
1r0
_
It seems that _r(any) should be converted to infinity - and _x and __x
too I think. This is in Raul's area.
If you have a dependency on the internal representation of infinity it
will be on you to update it.
Henry Rich
On 1/24/2023 9:00 PM, Ian Clark wrote:
j903 accepts -- but j904 rejects -- this way of defining rational infinity:
_r1
|ill-formed number
| _r1
| ^
JVERSION
Engine: j904/j64arm/darwin
Beta-k: commercial/2023-01-24T04:42:28
Library: 9.04.10
Qt IDE: 2.0.3/6.2.4(6.2.4)
Platform: Darwin 64
Installer: J904 install
InstallPath: /applications/j904
Contact: www.jsoftware.com
A workaround is to use 1r0 instead:
1r0
_
datatype 1r0
rational
Not a lot of j-ers willl have a use for rational [minus] infinity, but IMO
a beginner might find it more intuitive to define it as _r1 rather than 1r0
. Maybe it's no big deal in itself, but it breaks 3 addons, viz: math/cal,
math/uu -- and in consequence math/tabula:
load'math/uu' NB. Launch UU only
|ill-formed number in script, executing monad 0!: 0
|any word beginning with a digit or _ must be a valid number
| BADRAT=: __r1
| ^
|[-33] /applications/j904/addons/math/uu/uu.ijs
load'math/cal'
|ill-formed number in script, executing monad 0!: 0
|any word beginning with a digit or _ must be a valid number
| BAD_EXE_VALUE=: __r1
| ^
|[-92] /applications/j904/addons/math/cal/cal.ijs
So I'd call it a bug.
There's been plenty of time to discover this. Sorry it's taken me so long.
Ian Clark
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