#10836: primitive root is broken
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Reporter: kcrisman | Owner: was
Type: defect | Status: needs_review
Priority: critical | Milestone: sage-4.7
Component: number theory | Keywords:
Author: Karl-Dieter Crisman | Upstream: Reported upstream.
Developers deny it's a bug.
Reviewer: | Merged:
Work_issues: |
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Comment(by dsm):
I think maybe there's a little too much duplication with all the branches?
ISTM it's simpler to implement the condition exactly from the definition
given, with something like
{{{
if ((n == 4) or (n % 2 == 1 and n.is_prime_power()) or
(n % 2 == 0 and n % 4 != 0 and (n//2).is_prime_power())):
return ans
}}}
where each condition group matches exactly one of the classes of allowed
arguments in the docstring. I find this is also marginally faster on
average for successful calls. But I think we should check n for the
existence of a primitive root before we call pari, because when testing it
I came across this (4.6.2):
{{{
sage: factor(1729)
7 * 13 * 19
sage: time primitive_root(1729)
[... several minutes go by, so I have no idea if this eventually returns a
value or not ...]
}}}
Similarly for 2465, 3458, 4930. This is a pari bug not an interface bug,
as working directly with the console shows the same issue.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10836#comment:8>
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