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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