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?
