On Wed, Nov 4, 2009 at 2:43 PM, William Stein wrote:
> sage: Integers(7)(3) in ZZ
> True
I found this one funny:
sage: a = Integers(7)(3)
sage: a in ZZ
True
sage: a in QQ
False
In the same vein:
sage: b = Integers(11)(3)
sage: a in ZZ
True
sage: b in ZZ
True
sage: a + b
On Wed, Nov 4, 2009 at 8:35 AM, Vincent D <20100.delecr...@gmail.com> wrote:
>
> I understand now (and agree on) the design: sqrt(2) is symbolic and
> any sage expression containing a symbolic expression is also symbolic.
> But, considering the non comparison, it seems to give a set theoritic
> co
I understand now (and agree on) the design: sqrt(2) is symbolic and
any sage expression containing a symbolic expression is also symbolic.
But, considering the non comparison, it seems to give a set theoritic
contradiction:
sage: sqrt(2) in RR
True
And RR is an ordered field.
I think it goes in
> Should I expect
>
> sage: SR(1) + SR(2)
> 1 + 2
>
> just because
>
> sage: SR(x) + SR(2)
> x + 2
And why would "1 + 2" be wrong/bad or whatever?
Can you give a suggestion what I must input to sage to exacly get an
expression 1+2 in sage, i.e. an expression tree
+
/ \
1 2
?
It all
> Symbolic Ring
> sage: SR(1) > SR(2)
> 1 > 2
> because it returns:
> sage: x > 2
> x > 2
> if x is symbolic.
Right. And of course it doesn't say whether that is true or false.
That's just an expression. Only when one asks to transform that into a
boolean value, computation is started.
Challen
Dear William,
> This is completely orthogonal to the real question, which is about
> design. You've replaced the question of whether or not sqrt(2) > 1
> should be *simplified* automatically, by the question of how to do
> such simplifications. How to do them, is a black box that can cha
On Tue, Nov 3, 2009 at 3:22 PM, Florent Hivert
wrote:
> +1 to no simplification...
>
> Rationale: I think indeed that it is very important that the type of the
> result of an operator depends only of the type of the operands and not of
> their actual values. If > is a constructor for symbolic equ
On Tue, Nov 3, 2009 at 3:05 PM, William Stein wrote:
> This reminds me of / being a constructor for elements of QQ, no matter
> what, i.e., a/b for a and b both integers (with b!=0) is a rational,
> no matter what:
>
> sage: type(2/3)
>
> sage: type(2/1)
>
>
> This was an important design decis
Burcin Erocal wrote:
> Hi Jason,
>
> On Sat, 31 Oct 2009 19:58:56 -0500
> Jason Grout wrote:
>
>> I think it's kind of weird that:
>>
>> sqrt(2)>1
>>
>> does not return True automatically. I realize it's because symbolic
>> expressions do not automatically do comparisons, but maybe we ought
>
Hi,
On Sun, 1 Nov 2009 03:54:05 -0800 (PST)
Vincent Delecroix <20100.delecr...@gmail.com> wrote:
> I agree that sqrt(2) > 1 ;) the problem is the one Jason has
> developed : the comparison returns a symbolic expression !
>
> Morever, It works well for min and max functions :
> {{{
> sage: max(
Hi Jason,
On Sat, 31 Oct 2009 19:58:56 -0500
Jason Grout wrote:
> I think it's kind of weird that:
>
> sqrt(2)>1
>
> does not return True automatically. I realize it's because symbolic
> expressions do not automatically do comparisons, but maybe we ought
> to make an exception for symbolic
Hi,
I agree that sqrt(2) > 1 ;) the problem is the one Jason has
developed : the comparison returns a symbolic expression !
Morever, It works well for min and max functions :
{{{
sage: max(sqrt(2), 1)
sqrt(2)
sage: min(sqrt(2), 1)
1
}}}
Why max(sqrt(2), 1) not a symbolic expression ?
Vincent
Florent Hivert wrote:
> sage: x = sqrt(2)
> sage: x in RR
> True
> sage: x > 1
> sqrt(2) > 1
> sage: bool(x > 1)
> True
I think it's kind of weird that:
sqrt(2)>1
does not return True automatically. I realize it's because symbolic
expressions do not automatically do comparisons, but maybe we
Hi Vincent,
> I'm just in trouble with the behavior of sqrt(n) when n is an integer,
> because of the following:
> {{{
> sage: x = sqrt(2)
> sage: x in RR
> True
> sage: x > 1 # a boolean expected
> x > 1 # a symbolic expression obtained
> }}}
>
> It could be avoided by forcing the
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