limit not correctly computed by maxima

[ppurka]

This is taken from the google notebook bug report page.

sage: limit(tanh(x),x=0)            
x

On the other hand, this works

sage: limit(tanh(x),x=0,taylor=True)            
0

It is a bug in Maxima, and is still present in sage-5.0beta8. This beta apparently has maxima-5.26, the latest released version of Maxima.

---

Update: It has been fixed upstream. It is in maxima-5.27

---

Patch attached with doctest.
Apply attachment: trac_12708-doctest_limit.patch

Upstream: Fixed upstream, in a later stable release.

Component: calculus

Keywords: maxima limit

Author: Punarbasu Purkayastha

Reviewer: Karl-Dieter Crisman

Merged: sage-5.9.beta0

Issue created by migration from https://trac.sagemath.org/ticket/12708

[ppurka]

Upstream: Reported upstream. Little or no feedback.

[ppurka]

comment:1

Reported upstream

[kcrisman]

comment:2

Yup.

Maxima 5.26.0 http://maxima.sourceforge.net
using Lisp ECL 11.1.1
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) limit(tanh(x),x,1);
(%o1)                               tanh(1)
(%i2) limit(tanh(x),x,0);
(%o2)                                  x

Ah, ppurka, you already reported upstream... in the meantime I had already created one. I closed the duplicate, I guess we were both working on this at the same time. Sorry.

[ppurka]

Stopgaps: todo

[ppurka]

Description changed:

--- 
+++ 
@@ -11,3 +11,7 @@
 0
 ```
 It is a bug in Maxima, and is still present in sage-5.0beta8. This beta apparently has maxima-5.26, the latest released version of Maxima.
+
+---
+
+Update: It has been fixed upstream. We should upgrade to the next stable version of Maxima when it is released.

[ppurka]

Changed upstream from Reported upstream. Little or no feedback. to Fixed upstream, but not in a stable release.

[ppurka]

Changed upstream from Fixed upstream, but not in a stable release. to Fixed upstream, in a later stable release.

[ppurka]

Description changed:

--- 
+++ 
@@ -14,4 +14,5 @@
 
 ---
 
-Update: It has been fixed upstream. We should upgrade to the next stable version of Maxima when it is released.
+Update: It has been fixed upstream. It is in maxima-5.27
+

[kcrisman]

comment:5

Maxima 5.28 is now out.

[kcrisman]

comment:6

This should be fixed by #13364.