I get different behavior for trig functions at poles depending on how I evaluate them. For example:
f(x)=tan(x)^2-tan(x)
f(pi/2)
gives 0, which is disturbing.
Yet
f(x)=tan(x)*(tan(x)-1)
f(pi/2)
gives Infinity.
And,
tan(pi/2)^2-tan(pi/2)
gives
Infinity.
What's going on here?
This is a bug in Pynac. I opened a ticket on trac (#13587).
Thanks for the report.
Maxima behaves better:
sage: maxima('f(x):=tan(x)^2-tan(x)')
sage: maxima('f(%pi/2)')
....
....
....
Maxima ERROR:
tan: %pi/2 isn't in the domain of tan.
# the same error messages in:
sage: maxima('f(x):=tan(x)*(tan(x)-1)')
sage: maxima('f(%pi/2)')
sage: maxima('tan(%pi/2)^2-tan(%pi/2)')
Asked: 2012-10-08 14:35:55 +0100
Seen: 441 times
Last updated: Oct 08 '12
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