Barton Willis wrote:
> maxima-bounces at math.utexas.edu wrote on 08/28/2008 09:01:21 AM:
>
>
>> I'm not sure what is implemented, but the following sequence:
>>
>> x: inf;
>> x-x;
>> could result in zero, because it is the same infinity.
>> so should (x^2-1)-(x+1)*(x-1).
>>
>> However,
>> y:inf;
>> x-y should result in undefined.
>> Getting undefined arithmetic right would be just as important.
>>
>> Labeling each unique inf with an identifier is a way to do this.
>
> No, my code doesn't tag infinities this way. If we simply tagged
> each infinity with a gensym identifier, it wouldn't be all that
> hard to do, but getting through the test suite might be a chore.
How would such a tagged inf be printed? Will it be printed inf<junk>?
Or just inf?
With or without tagging, I'm not sure I like the example of x-x
returning 0, but inf-inf being undefined. I find that rather confusing.
Ray