# How to write equations with automatic equation numbering like \label{ref} in latex? [duplicate]

\begin{align} a = b \label{my equation} \end{align}

Equation \ref{my equation} is my equation.

I plan on editing my question Alternative representation of the covariant derivative? to make it more compact and concise, but it would be nice to save time and not have to renumber all of the equations manually a third time.

• As linked, there isn't the ability to do it automatically, you have to use \tag{} (MathJax doesn't process it). Curiously, however, using $\ref{ref1}$ in the body does produce a (dead) hyperlink. Mar 3, 2014 at 14:57
• It's worth noting that you don't need to tag every equation in your posts - just the ones that you refer to later on. If you have a quick browse you'll see that very few posts use them at all. You certainly don't need to tag substages of a calculation. Tagging is also a form of emphasis, but emphasis is lost if you use it on a lot of text, so it should be used only on the bits that really matter. See? Mar 3, 2014 at 17:04

\tag{something to refer back to}
$$C^2 = A^2 + B^2 \,. \tag{PT}$$
You have to type the refernces yourself. I tend to use *, **, $\dag$ and $\ddag$, or (as above) mnemonics for Physics SE posts.