#20084: residue: mathematically wrong output
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Reporter: behackl | Owner:
Type: defect | Status: new
Priority: critical | Milestone: sage-7.1
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by behackl):
The most elegant solution would of course be the automatic simplification
of expressions like `2^(something/log(2)) --> exp(something)`, such that
{{{
sage: 2^(2*pi*I/log(2))
1
}}}
However, I'm not sure if that can be achieved so easily.
A second suggestion would be something like
{{{diff
diff --git a/src/sage/symbolic/expression.pyx
b/src/sage/symbolic/expression.pyx
index 3a5c864..175bcad 100644
--- a/src/sage/symbolic/expression.pyx
+++ b/src/sage/symbolic/expression.pyx
@@ -4076,7 +4076,7 @@ cdef class Expression(CommutativeRingElement):
a = 0
if a == infinity:
return (-self.subs({x: 1/x}) / x**2).residue(x == 0)
- return self.subs({x: x+a}).series(x == 0, 0).coefficient(x, -1)
+ return self.subs({x: x+a}).canonicalize_radical().series(x == 0,
0).coefficient(x, -1)
def taylor(self, *args):
r"""
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/20084#comment:1>
Sage <http://www.sagemath.org>
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