Admittedly, the author of this thread did not consider the case in the
list of targets but when comparing 'conjugate' to 'imag_part' in Sage
I was surprized to see the following results.
sage: Q. = QuaternionAlgebra(SR, -1, -1)
sage: a,b,c=var('a,b,c')
sage: q = x + a*i + b*j + c*k
sage: conjugate
Le mardi 20 septembre 2016 04:02:16 UTC+2, Bill Page a écrit :
>
> In keeping with Richard's suggestion, in Sage I think a good
> _algebraic_ definition of 'real' is
>
> bool(x/2+conjugate(x)/2 == x)
>
why not bool(SR(x).imag_part()==0) ?
>
> So
>
> sage: def RN(x):
> : try:
On 2016-09-19 19:51, Thierry wrote:
you
should first remove SR(2.3) and 2*pi from your first list
That's a problem with the Symbolic Ring. Obviously, it doesn't coerce to
a real field (since it contains things like "sin(x)") but these
constants *should* coerce.
Anyway, I can always special-
In keeping with Richard's suggestion, in Sage I think a good
_algebraic_ definition of 'real' is
bool(x/2+conjugate(x)/2 == x)
So
sage: def RN(x):
: try:
: return bool(x/2+conjugate(x)/2 == x)
: except:
: return false
which also works whenever conjuga
If arg(x) is 0 and x is a number, then it is a real number. Maxima calls
this carg() for complex arg.
Carg will also work for some things that are not of numeric type, but
symbolic in some way.
.
Like sqrt(x^2+y^2) is real if domain=real
Good luck
On Monday, September 19, 2016 at 7:37:18
Hi,
On Mon, Sep 19, 2016 at 06:54:29PM +0200, Jeroen Demeyer wrote:
> On 2016-09-19 18:37, Travis Scrimshaw wrote:
> >The closest I can get is "foo in RR". This fails for CC(2.3, 0), but I
> >consider that to be a real number.
>
> I would say it's a complex number which happens to have a real val
On 2016-09-19 18:37, Travis Scrimshaw wrote:
The closest I can get is "foo in RR". This fails for CC(2.3, 0), but I
consider that to be a real number.
I would say it's a complex number which happens to have a real value.
But it is not a real number. It's the difference between *coercion* and
The closest I can get is "foo in RR". This fails for CC(2.3, 0), but I
consider that to be a real number.
Best,
Travis
On Monday, September 19, 2016 at 9:37:18 AM UTC-5, Jeroen Demeyer wrote:
>
> Hello,
>
> is there a simple way to check in Sage that something is a real number
> in some form?
