It's not a tolerant comparison (not that it matters for comparing 0 with
0!). If it was, they would use the standardese "if A is tolerantly-equal-to
B". Also section 12.2.1 has an informal note listing functions which use
comparison-tolerance, and the list does not include Logarithm.
Jay.
On 13 July 2016 at 12:21, Juergen Sauermann <juergen.sauerm...@t-online.de>
wrote:
> Hi Jay,
>
> I see. Which leaves the question if "equal" shall be strict or within
> *⎕IO*.
>
> Since we are dealing with real numbers (and therefore often rounding
> errors) within *⎕IO*
> makes more sense to me but the standard does not mention *⎕IO* for *⍟*.
>
> /// Jürgen
>
>
> On 07/13/2016 01:05 PM, Jay Foad wrote:
>
> My ISO ("First edition 2001-02-01") says:
>
> Evaluation Sequence:
> If either of A or B are not numbers signal domain-error.
> If A and B are equal, return one.
> If A is one, signal domain-error.
> Set A1 to the natural-logarithm of A.
> Set B1 to the natural-logarithm of B.
> Return B1 divided-by A1.
>
> 0⍟0 falls into the "A and B are equal" case.
>
> Jay.
>
> On 13 July 2016 at 11:04, Juergen Sauermann <juergen.sauerm...@t-online.de
> > wrote:
>
>> Hi Kacper,
>>
>> my ISO (June 9, 2000) says DOMAIN ERROR.
>>
>> More precisely, they say that A⍟B is (⍟A)÷(⍟B) and then that ⍟0 gives
>> DOMAIN ERROR.
>>
>> /// Jürgen
>>
>>
>> On 07/12/2016 11:43 PM, Kacper Gutowski wrote:
>>
>> According to ISO, 0⍟0 should be one.
>> GNU APL gives:
>>
>> 0⍟0
>> DOMAIN ERROR
>> 0⍟0
>> ^^
>>
>> -k
>>
>>
>>
>>
>>
>
>
