#(0 0 0) is the additive identity in that case
> On 25 Mar 2020, at 12:38, Richard O'Keefe <rao...@gmail.com> wrote:
>
> There are situations where #+ and #sum make sense but there is no additive
> identity. Here is an example:
> #((1 2 3) (4 5 6) (7 8 9)) sum
>
> On Tue, 24 Mar 2020 at 02:46, James Foster <smallt...@jgfoster.net> wrote:
>>
>>
>>> On Mar 23, 2020, at 6:06 AM, Sven Van Caekenberghe <s...@stfx.eu> wrote:
>>>
>>> What you found out now is that the clever trick used to avoid picking an
>>> additive identity (picking an element, counting it twice and then
>>> subtracting it) leads to a loss of precision when floating point numbers
>>> are involved. This is an important issue.
>>
>> If this approach is to be preserved, then each class should have an additive
>> identity so instead of adding and subtracting an object, we let the object
>> tell us its zero.
>>
>> James
>
