Thanks for your efforts, Dmitrii -- I will create a ticket since this
must be fixed.

John

On 8 February 2010 16:45, Dima Pasechnik <[email protected]> wrote:
> IHMO it's just the usual fp hell: data gets moved from registers into
> memory and back, etc (but maybe I am wrong here, don't know)
>
> Anyway, there is a way to avoid taking sqrt at all, just solve the
> equation f(x^2)=0, not f(x)=0.
>
> Dmitrii
>
> On Feb 8, 11:26 pm, YannLC <[email protected]> wrote:
>> > It can do sqrt(-734/3), but fails on
>> > sqrt(-244.6666666666667? + 0.?e-39*I)
>> > for some reason.
>>
>> > Dmitrii
>>
>> It's worse than failing, it also changes the value:
>>
>> sage: x = polygen(QQbar)
>> sage: f = 3*x^4 - 4*x^3 - 1046148*x^2 - 335575956*x - 30288853512
>> sage: rts = f.roots(multiplicities=False)
>> sage: r1 = rts[1]
>> sage: r1
>> -244.6666666666667? + 0.?e-39*I
>> sage: r1.sqrt()
>> ...
>> AttributeError: 'sage.rings.real_mpfi.RealIntervalFieldElement' object
>> has no attribute 'argument'
>> sage: r1
>> -734/3
>
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