Hi,
I found a strange issue:
ex = (arctan(1/2) + arcsin(sqrt(5)/5) == arctan(4/3))
bool(ex)And it gives False.
A simple numeric approximation allows to see that it's true, and wolfram alpha for instance gives the correct answer. But why is it like that and how can I fix it?
Thanks
Actually, Sage returns False whenever it does not manage to prove that an equality is true or false. Therefore only True is a mathematically meaningful output for such a test.
Oh, that's problematical. It's a shame not to be able to verify such an equality. Really, there is no way?
I tried:
sage: tan( arctan(1/2) + arcsin(sqrt(5)/5) - arctan(4/3) ).simplify_full()
0
Usually, it is a good idea to put all expressions on one side. The symbolic expression simplifier has a simpler work.
Your way is also working, however I find weird having to add a 'tan(...)' to the expression to prove that it's equal to 0. Indeed, tan(0)=0 but that does not always work (tan(2k*pi)=0 too)
Asked: 8 years ago
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Last updated: Feb 25 '17
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In sagecell,
giac('simplify(tExpand((arctan(1/2) + arcsin(sqrt(5)/5) - arctan(4/3))))')returns 0.tExpandis a shortcut for expand trascendental expressions.Seems to work. Thanks for the terminology.