#8459: broken translatin of polylog from Maxima
----------------------------+-----------------------------------------------
Reporter: robert.marik | Owner: burcin
Type: defect | Status: needs_review
Priority: major | Milestone:
Component: symbolics | Keywords: symbolics
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
----------------------------+-----------------------------------------------
Changes (by robert.marik):
* cc: burcin (added)
* status: new => needs_review
Comment:
The patch is attached. Still have behavior which I do not understand:
log(-x^2 + 1)*log(x) + 1/2*polylog(2, -x^2 + 1) evaluates numerically at
x=1/2 only if it is obtained from direct input and not from Maxima.
{{{
----------------------------------------------------------------------
| Sage Version 4.3.3, Release Date: 2010-02-21 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: f(x)=integrate(ln(1-x^2)/x,x)
sage: f
x |--> log(-x^2 + 1)*log(x) + 1/2*polylog(2, -x^2 + 1)
sage: g(x)=log(-x^2 + 1)*log(x) + 1/2*polylog(2, -x^2 + 1)
sage: g
x |--> log(-x^2 + 1)*log(x) + 1/2*polylog(2, -x^2 + 1)
sage: bool(f==g)
False
sage: bool(f._repr_()==g._repr_())
True
sage: g(1/2).n()
0.688640713882747
sage: f(1/2).n()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/opt/sage-4.3.3-i686-Linux/<ipython console> in <module>()
/opt/sage/local/lib/python2.6/site-packages/sage/symbolic/expression.so in
sage.symbolic.expression.Expression.n
(sage/symbolic/expression.cpp:17036)()
TypeError: cannot evaluate symbolic expresssion numerically
sage:
}}}
Any idea what happens?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8459#comment:1>
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