#9438: IntegerMod_int.log has side-effect in Pari
--------------------------------+-------------------------------------------
Reporter: SimonKing | Owner: AlexGhitza
Type: defect | Status: new
Priority: critical | Milestone: sage-4.5
Component: basic arithmetic | Keywords: log finite field pari
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Motivated by a bug hunt for #2420, I found:
{{{
sage: R.<a, b> = QQ[]
sage: b._pari_()
b
sage: GF(7)(5).log()
5
sage: b._pari_()
Mod(3, 7)
}}}
The reason is that in the {{{log}}} method, the string
{{{
'b=Mod(%s,%s); if(znorder(b)!=eulerphi(%s),-1,znlog(%s,b))'%(b,
self.__modulus.sageInteger,
self.__modulus.sageInteger, self)
}}}
is evaluated in {{{pari}}}, so that afterwards {{{pari('b')}}} isn't doing
what it should.
Since this bug is triggered whenever a GAP representation of a finite
field element is created, I mark this ticket "critical". I hope "basic
arithmetic" is the right component.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9438>
Sage <http://www.sagemath.org>
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