Maxima, from memory supplemented with an experiment with 5.27, has
a) infinity, which is the infinity of the (one-point compactification of
the) complex plane
b) inf, which is the positive one of the two-point compactification of the
reals ("plus infinity")
c) minf, which is the negative one of the two-point compactification of the
reals ("minus infinity")
The back-translation from Maxima to Sage appears to confuse inf and
infinity.
James Davenport
PS Note the confusing fact that the reals are a subset of the complexes,
but the usual (two-point) compactification of the reals is NOT a subset of
the compactification of the complexes.
On Monday, 19 August 2013 19:17:28 UTC+1, kcrisman wrote:
>
>
>
> On Monday, August 19, 2013 1:55:04 PM UTC-4, Vince wrote:
>>
>> When computing the limit of a function I don't quite seem to be getting
>> the behaviour that I expected.
>>
>> ---
>> sage: f(x) = 1 / x
>> sage: print f.limit(x=0)
>> sage: print f.limit(x=0, dir='minus')
>> ---
>>
>> The first limit returns infinity, but I would expect it to return that
>> the limit is not defined.
>>
>
> I think we have an unsigned infinity and a signed infinity. It should
> return the former, from Maxima.
>
>
>
>
>> The second (directional) limit confirms this (it returns -infinity). I
>> was assuming that the default 'direction' for a limit is None and that a
>> two directional limit would be computed (which in this case does not
>> exist). Here's some of the help file that shows why I am perhaps confused:
>>
>> ---
>> INPUT:
>>
>> - ``dir`` - (default: None); dir may have the value
>> 'plus' (or '+' or 'right') for a limit from above,
>> 'minus' (or '-' or 'left') for a limit from below, or may be omitted
>> (implying a two-sided limit is to be computed).
>> ---
>>
>> If anyone could clarify this I'd appreciate it.
>>
>> Vince
>>
>
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