Re: issquare on quadratic forms

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

* Bill Allombert [2017-12-01 19:03]:
> On Fri, Dec 01, 2017 at 12:40:14PM -0500, Sam Steingold wrote:
>> It appears that once upon a time issquare worked on t_QFR and t_QFI, but
>> now I get
>>   ***   incorrect type in issquare (t_QFI).
>> and
>>   ***   incorrect type in issquare (t_QFR).
>> What has happened?
> 
> From CHANGES-2.4:
> 
>    10- issquare(t_QFI or t_QFR) now is an error. Use explicitly
>        issquare(component(x,1)) if you relied(?) on the old behaviour

Note that

  ? Qfb(2, 1, 3)^2
  %1 = Qfb(2, -1, 3)

whereas the old issquare code returned 0 in this case: it used to check
whether the 'a' coefficient was a rational square (which does not make
sense since all natural computations via '*' or '^' operators occur in
the class group).

Cheers,

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite de Bordeaux         Fax: (+33) (0)5 40 00 21 23
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~kbelabas/
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`