TITLE: What do the $+,-$ mean in limit notation, like$\lim\limits_{t \to 0^+}$ and $\lim\limits_{t \to 0^-}$?
QUESTION [14 upvotes]: I'm working on Laplace Transforms and have got to a section where they are talking about zero to the power plus or minus and that they are different. I can't remember what this means though.
It's generally used in limits.
$\lim\limits_{t\to 0^-}$ or $\lim\limits_{t\to 0^+}$
Any help would be much appreciated.

REPLY [9 votes]: And a good, visual example could be something like
                            
$$\begin{align}
\lim_{x\to x_0^-}f&=y_1\\
\lim_{x\to x_0^+}f&=y_2
\end{align}$$