#9466: square root with all=True should not return ValueError but empty list
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Reporter: mstreng | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone: sage-5.11
Component: algebra | Resolution:
Keywords: sd23 sd51 sqrt all | Merged in:
Authors: Marco Streng | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Dependencies:
Stopgaps: |
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Changes (by {'newvalue': u'Marco Streng', 'oldvalue': ''}):
* keywords: => sd23 sd51 sqrt all
* cc: ruckers (added)
* author: => Marco Streng
Old description:
> With Sage 4.4.4 and no relevant patches, I got the following:
> {{{
> sage: FiniteField(3)(2).sqrt(all = True)
> []
>
> sage: 2.sqrt(extend = False, all = True)
> ValueError: square root of 2 not an integer
>
> sage: FiniteField(next_prime(2^100))(2).sqrt(extend = False, all = True)
> ValueError: self must be a square
>
> sage: _.<a>=FiniteField(9)
> sage: a.sqrt(extend = False, all = True)
> ValueError: must be a perfect square.
> }}}
>
> At sage days 23 we agreed that square root with all=True should not raise
> an error. If no square roots exist, then it should return an empty list.
>
> Right now, it returns an empty list for elements of small prime finite
> fields, but raises an error for integers, elements of large prime finite
> fields, and elements of non-prime finite fields.
New description:
With Sage 4.4.4 and no relevant patches, I got the following:
{{{
sage: FiniteField(3)(2).sqrt(all = True)
[]
sage: 2.sqrt(extend = False, all = True)
ValueError: square root of 2 not an integer
sage: FiniteField(next_prime(2^100))(2).sqrt(extend = False, all = True)
ValueError: self must be a square
sage: _.<a>=FiniteField(9)
sage: a.sqrt(extend = False, all = True)
ValueError: must be a perfect square.
}}}
At sage days 23 we agreed that square root with all=True should not raise
an error. If no square roots exist, then it should return an empty list.
Right now, it returns an empty list for elements of small prime finite
fields, but raises an error for integers, elements of large prime finite
fields, and elements of non-prime finite fields.
apply
* [attachment:9466.patch]
--
Comment:
Does anyone know who user "ruckers" is? (s)he should be added to the list
of authors
apply 9466.patch
--
Ticket URL: <http://trac.sagemath.org/ticket/9466#comment:5>
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