#14685: error in the computing of the approximate order in LazyPowerSeries
-----------------------------+----------------------------------------------
Reporter: MatthieuDien | Owner: sage-combinat
Type: PLEASE CHANGE | Status: new
Priority: major | Milestone: sage-5.10
Component: combinatorics | Keywords: LazyPowerSeries aorder
approximate order
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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Hi,
I found a bug in the LazyPowerSeries class of package combinat.
There is mistake in the computing of the approximate order of a serie.
A demonstration of the bug :
{{{
sage: R = LazyPowerSeriesRing(QQ)
sage: B = R([0,0,0,1,0])
sage: B.aorder
0
sage: B.coefficients(10)
[0, 0, 0, 1, 0, 0, 0, 0, 0, 0]
sage: B.aorder
1
}}}
Here, a patch :
{{{
diff --git a/sage/combinat/species/series.py
b/sage/combinat/species/series.py
--- a/sage/combinat/species/series.py
+++ b/sage/combinat/species/series.py
@@ -631,6 +631,7 @@
self.aorder += 1
ao += 1
else:
+ self.order = ao
break
#Try to recognize the zero series
@@ -643,8 +644,17 @@
self.order = inf
return
- if ao < n:
- self.order = ao
+ if self.order == unk:
+ while ao < n:
+ if self._stream[ao] == 0:
+ self.aorder += 1
+ ao += 1
+ else:
+ self.order = ao
+ break
+
+ # if ao < n:
+ # self.order = ao
if hasattr(self, '_reference') and self._reference is not None:
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14685>
Sage <http://www.sagemath.org>
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