#8612: potentially horrible multimodular matrix echelon bug
------------------------------+---------------------------------------------
Reporter: was | Owner: was
Type: defect | Status: new
Priority: blocker | Milestone: sage-4.4
Component: linear algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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I was browsing the code in matrix/misc.pyx, and noticed:
{{{
These lines are in misc.pyx:
if not proof:
verbose("Not checking validity of result (since
proof=False).", level=2, caller_name="multimod echelon")
break
d = E.denominator()
hdE = long(E.height())
if True or hdE * self.ncols() * height < prod:
break
M = prod * p*p*p
}}}
Notice the "if True" -- that disables proof checking no matter what!!
This must be removed. This could get hit in rare cased by, e.g., the
modular symbols code, and it would lead to weird inconsistencies later
on.... which is something we've seen on big examples.
I'm guessing this was the result of disabling proof checking while
developing the code, then never switching it back.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8612>
Sage <http://www.sagemath.org>
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