Hola,
I'm stuck at the problem of determinating whether a given expression is
known to be real number or not.
So far, I've been testing this either
with
expr.is_real()
or
expr in
RR
succesfully.
Now, if I give Sage this expression of real number:
-1/12*pi + 1/12*sqrt(16*pi + pi^2 + 256) + 4/3
the following results will occur:
http://aleph.sagemath.org/?z=eJxLVLBV0DXUNzTSKshU0FYAs4oLi0o0DM0gIgWZcUZAysjUTBNImegbc3EVFGXmlSgk6mUWxxelJuZoaMKFFDLzFIKCAHCUFik%3D
On the other hand, non-real value below:
arccos(2)
would produce the very same results, though it should give opposite results
for at least 1 test:
http://aleph.sagemath.org/?c=a+%3D+arccos%282%29%0A%0Aprint+a.is_real%28%29%0A%0Aprint+a+in+RR
Is there any other/standard way to test membership to real numbers?
Is this a bug or is it covered somewhere else?
Duc Trung Ha
Sage Version 4.8, Release Date: 2012-01-20
Intel(R) Core(TM) i5-2410M CPU @ 2.30GHz
Kubuntu 12.04
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