#7212: [with patch, needs review] steenrod algebra multiplication bug
--------------------------+-------------------------------------------------
Reporter: jhpalmieri | Owner: tbd
Type: defect | Status: new
Priority: minor | Milestone: sage-4.2
Component: algebra | Keywords:
Work_issues: | Author: jhpalmieri
Reviewer: | Merged:
--------------------------+-------------------------------------------------
From sage-support:
{{{
I have Sage 4.1.1 install on a server, and I run the following code,
which outputs the following error:
sage: A3=SteenrodAlgebra(3)
sage: A3.P(36,6)*A3.P(27,9,81)
---------------------------------------------------------------------------
KeyError Traceback (most recent call
last)
/home/user_bob/<ipython console> in <module>()
/usr/local/sage-4.1.1/local/lib/python2.6/site-packages/sage/structure/
element.so in sage.structure.element.RingElement.__mul__ (sage/
structure/element.c:9956)()
/usr/local/sage-4.1.1/local/lib/python2.6/site-packages/sage/structure/
element.so in sage.structure.element.RingElement._mul_ (sage/structure/
element.c:10021)()
/usr/local/sage-4.1.1/local/lib/python2.6/site-packages/sage/algebras/
steenrod_algebra_element.pyc in _mul_(self, other)
925 new_dict = milnor_multiplication
(mono1, mono2)
926 else:
--> 927 new_dict = milnor_multiplication_odd
(mono1, mono2, p=p)
928 for new_mono in new_dict:
929 if result.has_key(new_mono):
/usr/local/sage-4.1.1/local/lib/python2.6/site-packages/sage/algebras/
steenrod_milnor_multiplication_odd.pyc in milnor_multiplication_odd
(m1, m2, p)
225 t = tuple(diagonal[:i+1])
226 if result.has_key((e,t)):
--> 227 result[(e,t)] = F(coeff + result[t])
228 else:
229 result[(e,t)] = F(coeff)
KeyError: (26, 8, 86)
}}}
This is because of a simple bug: instead of {{{result[t]}}}, it should be
{{{result[(e,t)]}}}.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7212>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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