Hmmm... Uting TLAs :
sage: sqrt(4-4*x).simplify()
sqrt(-4*x + 4)
sage: sqrt(4-4*x).simplify_full()
sqrt(-4*x + 4)
sage: sqrt(4-4*x).canonicalize_radical()
2*I*sqrt(x - 1)
WTF ? BTW :
sage: bool(sqrt(4-4*x)==2*sqrt(1-x))
False
sage: bool((sqrt(4-4*x)/(2*sqrt(1-x)))==1)
False
sage: bool((sqrt(4-4*x)/(2*sqrt(1-x))).canonicalize_radical()==1)
True
QED. HTH,
--
Emmanuel Charpentier
Le lundi 3 juillet 2017 12:00:03 UTC+2, LudJam a écrit :
>
> I think I discovered a case where bool() of a symbolic expression returns
> false while it is true :
>
> bool(sqrt(-4*x+4)==sqrt(-x+1)*2)
> >>false
>
> I think the problem is that sage can't manage to simplify sqrt(-4*x+4)
> in sqrt(-x+1)*2
>
> sqrt(-4*x+4).full_simplify()
> >>sqrt(-4*x+4)
>
> P.S. : I tried with the assumption assume(x<1) but it doesn't changed
> anything...
>
> Le mercredi 2 avril 2008 23:42:15 UTC+2, Jason Grout a écrit :
>>
>> Timothy Clemans wrote:
>> > +1
>> >
>> > On Wed, Apr 2, 2008 at 12:12 PM, Jason Grout
>> > <jason...@creativetrax.com> wrote:
>> >> Currently, False is returned when bool() is called on a
>> SymbolicEquation
>> >> when the equation is really false *or* when it is not known whether
>> it
>> >> is true or false. This, of course, makes a return value of False
>> pretty
>> >> meaningless.
>> >>
>> >> Can I change this (per cwitty's suggestion) so that if it is not known
>> >> if a SymbolicEquation is false or true, an error is thrown?
>> >>
>> >> i.e.:
>> >>
>> >> sage: bool(x<x+1)
>> >> True
>> >> sage: bool(x>x+1)
>> >> False
>> >> sage: var('y')
>> >>
>> >> ***CURRENTLY***
>> >> sage: bool(x<y)
>> >> False
>> >>
>> >> ***Proposed***
>> >> sage: bool(x<y)
>> >> Error is thrown
>>
>>
>> This is now #2781. A preliminary patch is up there now.
>>
>> Jason
>>
>>
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at https://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/d/optout.
