id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,merged,author,reviewer,upstream,work_issues,branch,commit,dependencies,stopgaps
27304,Bug in factorization of simple symbolic expressions,egourgoulhon,,"As reported in this [https://ask.sagemath.org/question/45469 ask.sagemath question], we have currently (Sage 8.7.beta3):
{{{
sage: factor(2*exp(x) + exp(-x))
3*e^x
}}}
as well as
{{{
sage: factor(x*exp(-x) + exp(-x))
(x + 1)*e^x
}}}
Another example of erroneous result exhibited in https://groups.google.com/d/msg/sage-devel/ytLqIb4soLw/c14ZKGqcAAAJ is
{{{
sage: var('t u')
(t, u)
sage: L = (u + t)/(u - t)
sage: factor(L.substitute(t=sqrt(u)))
(u + 1)/(u - 1)
}}}
This bug is there since at least Sage 8.4.beta4. It is not in Sage 8.3, hence it must have been introduced between 8.4.beta0 and 8.4.beta4. It seems to have been introduced in #23835 (see comment:5).
",defect,positive_review,blocker,sage-8.8,symbolics,,"factor, exponential, pynac",rws bpage,,Benjamin Hackl,Emmanuel Charpentier,N/A,,u/behackl/simple-factorization-rational,7c2432ce2fdfe7eb905b91179a0fcaccef3d0a52,,