Hello,
Maybe abs() function have to be reconsidered, because I found other issues
with abs...
limit(abs(ln(x))-ln(x), x, 2) or limit(abs(ln(x))-ln(x), x, 2, '+') return
0 (OK), but limit(abs(ln(x))-ln(x), x, 2, '-') runs endless and I need to
interrupt it to stop calculating.. Same way with functions :
abs(cos(x))-cos(x) or abs(sin(x))-sin(x) or abs(sqrt(x))-sqrt(x) for x =
symbols('x', real=True)
But if I try : limit(abs(ln(x))-ln(x), x, a, '-') with a = symbols('a',
real=True), it returns (sign(log(a)) - 1)*log(a). Idem for the direction
'+' and without direction.
Le mercredi 11 février 2015 12:27:23 UTC+1, Christophe Bal a écrit :
>
> Hello.
>
> Maybe, it could be useful to have a abssimplify method that will try to
> simplify abs expressions.
>
> Christophe BAL
>
> Le 11 févr. 2015 11:54, "Arnaud Usciati" <[email protected] <javascript:>>
> a écrit :
> >
> > Hi,
> >
> > I found another error limit :
> > If x = symbols('x', positive=True), limit(tan(abs(x))/acosh(x), x, pi/2,
> '-') returns oo --> OK
> > If x = symbols('x', real=True), limit(tan(abs(x))/acosh(x), x, pi/2,
> '-') returns oo*sign(1/Subs(Derivative(re(_x), _x), (_x,), (0,))) !!
> >
> > I guess the first result is correct because sympy can evaluate abs(x) to
> x for x positive, but for x real it can't simplify the function and
> calculate the limit !
> >
> > Le samedi 7 février 2015 05:08:05 UTC+1, Ondřej Čertík a écrit :
> >>
> >> The limits will have to be debugged, essentially we just need to go
> >> step by step and see which routine returns the wrong answer.
> >>
> >> Ondrej
> >>
> >> On Fri, Feb 6, 2015 at 8:11 PM, Aaron Meurer <[email protected]>
> wrote:
> >> > Be sure to test against SymPy master. As Ondrej pointed out, this
> used to
> >> > work, but it got broken.
> >> >
> >> > Aaron Meurer
> >> >
> >> > On Fri, Feb 6, 2015 at 5:55 PM, Douglas Lohmann <[email protected]>
> wrote:
> >> >>
> >> >> In my test it's not a bug. You can explain better?
> >> >>
> >> >> In [9]: limit(abs(log(x)), x, 0, '+')
> >> >> Out[9]: oo
> >> >>
> >> >> It was already reported the bug to the bug list?
> >> >>
> >> >> Em sábado, 31 de janeiro de 2015 13:33:40 UTC-2, Arnaud Usciati
> escreveu:
> >> >>>
> >> >>> Hello,
> >> >>>
> >> >>> limit(abs(log(x)), x, 0, '+') should return +oo, but it returns
> >> >>> -oo*sign(log(_w)) !!!
> >> >>>
> >> >>>
> >> >> --
> >> >> You received this message because you are subscribed to the Google
> Groups
> >> >> "sympy" group.
> >> >> To unsubscribe from this group and stop receiving emails from it,
> send an
> >> >> email to [email protected].
> >> >> To post to this group, send email to [email protected].
> >> >> Visit this group at http://groups.google.com/group/sympy.
> >> >> To view this discussion on the web visit
> >> >>
> https://groups.google.com/d/msgid/sympy/b6cd9121-b2db-4979-8627-b4fcf9f98a99%40googlegroups.com.
>
>
> >> >>
> >> >> For more options, visit https://groups.google.com/d/optout.
> >> >
> >> >
> >> > --
> >> > You received this message because you are subscribed to the Google
> Groups
> >> > "sympy" group.
> >> > To unsubscribe from this group and stop receiving emails from it,
> send an
> >> > email to [email protected].
> >> > To post to this group, send email to [email protected].
> >> > Visit this group at http://groups.google.com/group/sympy.
> >> > To view this discussion on the web visit
> >> >
> https://groups.google.com/d/msgid/sympy/CAKgW%3D6L30%3Dh4-b6r2S_1c7tZ%3Deu8n7zFWcCBQOcTaN3f1MbnMA%40mail.gmail.com.
>
>
> >> >
> >> > For more options, visit https://groups.google.com/d/optout.
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups "sympy" group.
> > To unsubscribe from this group and stop receiving emails from it, send
> an email to [email protected] <javascript:>.
> > To post to this group, send email to [email protected]
> <javascript:>.
> > Visit this group at http://groups.google.com/group/sympy.
> > To view this discussion on the web visit
> https://groups.google.com/d/msgid/sympy/5feb0587-b775-4922-ba30-6841a41821af%40googlegroups.com
> .
> >
> > For more options, visit https://groups.google.com/d/optout.
>
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sympy.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sympy/9ed18d5e-ec21-4a8e-96f9-136a17a12720%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
