#7923: signed int overflow in givaro elements' __pow__ method
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Reporter: roed | Owner: AlexGhitza
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.3.1
Component: basic arithmetic | Keywords:
Work_issues: | Author: David Roe
Upstream: N/A | Reviewer:
Merged: |
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Description changed by roed:
Old description:
> {{{
> When 2^31 < q^2 < 2^32, one can get an overflow in exponentiation
> (because of the use of signed vs unsigned ints).
>
> This occurs for q=3^10.
> }}}
>
> {{{
> sage: K.<a> = GF(3^10)
> sage: b = a^9 + a^7 + 2*a^6 + a^4 + a^3 + 2*a^2 + a + 2
> sage: b^(71*7381) == (b^71)^7381
> False
> }}}
New description:
When 2^31^ < q^2^ < 2^32^, one can get an overflow in exponentiation
(because of the use of signed vs unsigned ints).
This occurs for q=3^10^.
{{{
sage: K.<a> = GF(3^10)
sage: b = a^9 + a^7 + 2*a^6 + a^4 + a^3 + 2*a^2 + a + 2
sage: b^(71*7381) == (b^71)^7381
False
}}}
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7923#comment:3>
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