#13742: No Permutation should be created that its method cannot handle
---------------------------------+------------------------------------------
Reporter: ncohen | Owner: sage-combinat
Type: defect | Status: needs_work
Priority: major | Milestone: sage-5.6
Component: combinatorics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Nathann Cohen | Merged in:
Dependencies: | Stopgaps:
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Comment (by dimpase):
another thing: one can still create a "permutation" which is not a
permutation, and get an error:
{{{
sage: p=Permutation([3,4,5,1])
sage: p.is_even()
---------------------------------------------------------------------------
IndexError Traceback (most recent call
last)
/usr/local/src/sage/sage-5.5.rc0/devel/sage-main/<ipython console> in
<module>()
/usr/local/src/sage/sage-5.5.rc0/local/lib/python2.7/site-
packages/sage/combinat/permutation.pyc in is_even(self)
859 """
860
--> 861 if self.signature() == 1:
862 return True
863 else:
/usr/local/src/sage/sage-5.5.rc0/local/lib/python2.7/site-
packages/sage/combinat/permutation.pyc in signature(p)
842 1
843 """
--> 844 return (-1)**(len(p)-len(p.to_cycles()))
845
846 #one can also use sign as an alias for signature
/usr/local/src/sage/sage-5.5.rc0/local/lib/python2.7/site-
packages/sage/combinat/permutation.pyc in to_cycles(self, singletons)
652 while next != cycleFirst:
653 cycle.append( next )
--> 654 l[next - 1], next = False, l[next - 1]
655 #Add the cycle to the list of cycles
656 if singletons or len(cycle) > 1:
IndexError: list index out of range
}}}
(many other functions of p will error out, too)
Any plans to deal with this?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13742#comment:18>
Sage <http://www.sagemath.org>
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