# Revision history [back]

### odd trig function behavior

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?