If arg(x) is 0 and x is a number, then it is a real number. Maxima calls
this carg() for complex arg.

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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 AM UTC-7, Jeroen Demeyer wrote:
>
> Hello,
>
> is there a simple way to check in Sage that something is a real number
> in some form? That is, I am looking for a predicate which returns True
> on all the following things:
>
> int(2)
> ZZ(2)
> float(2.3)
> QQ(23/10)
> RR(2.3)
> RDF(2.3)
> SR(2.3)
> 2*pi
>
> but not on things like
>
> "2.3"
> CC(2.3, 0)
> SR.symbol("x")
>
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