https://trac.sagemath.org/ticket/33692
On Monday, April 11, 2022 at 6:38:28 PM UTC-4 Nils Bruin wrote:
> That's a fairly straightforward thing to fix: it just means that the
> sage-to-maxima interface needs to learn how to translate "plus" and "minus"
> in limit expressions.
>
> The easiest way would be to tell the interface that "plus" and "minus" are
> symbols that need a hardcoded translation. A more subtle version would put
> a special translation in place for a symbolic "limit" to treat the
> direction argument separately.
>
> Perhaps a slightly cleaner way of triggering the error:
>
> function('f')
> limit(f(x),x=0,dir="-").simplify()
>
> Someone should file a bug report.
> On Monday, 11 April 2022 at 05:17:22 UTC-7 jkma...@gmail.com wrote:
>
>> `integrate()' function on non-elementary integrals outputs sometimes a
>> limit function, ie:
>> In: k = var("m", domain='positive', latex_name=r"\hat k" );
>> In: N_nr = integrate(k^2/(exp(k)+1), (k, 0, oo))
>> Out: `limit(1/3*k^3 - k^2*log(e^k + 1) - 2*k*dilog(-e^k) + 2*polylog(3,
>> -e^k), k, +Infinity, minus) + 3/2*zeta(3)`
>>
>> Analytically, the part under the limit is equal to 0 (compare to
>> mathematica's N_nr = Integrate[k^2/(Exp[k] + 1), {k, 0, Infinity}]
>>
>> On simplify, the engine tries to evaluate the limit using maxima and fails
>> In: N_nr.simplify()
>> Out: TypeError: ECL says: Error executing code in Maxima: limit:
>> direction must be either 'plus' or 'minus'; found: _SAGE_VAR_minus
>>
>> Something seems to be off from putting this sage expression to maxima.
>>
>> Version: Sage 9.3
>> OS: Windows 10 Pro, 21H2, x64
>>
>
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