#17892: Sage cannot work with Maxima's symbolic limit
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Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.6
Component: calculus | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Description changed by rws:
Old description:
> Maxima gives back limit expressions in some integral computation but Sage
> has no idea what that is. Consequently, working with the expression leads
> to failure:
> {{{
> sage: u(t) = exp(-(t-a)^2/(2*s^2)) + exp(-(t-b)^2/(2*s^2)) ; u(t);
> sage: integral(u(t)*exp(-I*k*t), t, -infinity, +infinity, hold=False)
> -limit(1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*a +
> sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*a*k) +
> 1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*b +
> sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*b*k), t, -Infinity, plus) +
> limit(1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*a +
> sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*a*k) +
> 1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*b +
> sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*b*k), t, +Infinity, minus)
> sage: _.simplify_full()
> ...
> TypeError: ECL says: Error executing code in Maxima:
> }}}
> Presumably a symbolic limit function would be necessary, and to connect
> it with what Maxima gives back.
>
> Is there a smaller example?
New description:
Maxima gives back limit expressions in some integral computation but Sage
has no idea what that is. Consequently, working with the expression leads
to failure:
{{{
sage: u(t) = exp(-(t-a)^2/(2*s^2)) + exp(-(t-b)^2/(2*s^2)) ; u(t);
sage: integral(u(t)*exp(-I*k*t), t, -infinity, +infinity, hold=False)
-limit(1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*a +
sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*a*k) +
1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*b +
sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*b*k), t, -Infinity, plus) +
limit(1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*a +
sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*a*k) +
1/2*sqrt(2)*sqrt(pi)*s*erf(1/2*(I*sqrt(2)*k*s^2 - sqrt(2)*b +
sqrt(2)*t)/s)*e^(-1/2*k^2*s^2 - I*b*k), t, +Infinity, minus)
sage: _.simplify_full()
...
TypeError: ECL says: Error executing code in Maxima:
}}}
Presumably a symbolic limit function would be necessary, and to connect it
with what Maxima gives back.
Is there a smaller example?
This is from http://ask.sagemath.org/question/26004/sage-65-maxima-
simplify_full-error/
--
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Ticket URL: <http://trac.sagemath.org/ticket/17892#comment:1>
Sage <http://www.sagemath.org>
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