E = m c2, where m is the mass and c is the speed of light.If the formula gets too long, you can display the formula on a line by itself, and put the explanatory ‘where’ clause on a new line:
E = m c2Aside: I have removed the punctuation after the displayed equation. People, and style manuals, argue about whether it should be retained or not. My argument is: extra punctuation in a mathematical formula might be confused as a symbol of the formula; the end of line provides visible punctuation; I leave it out. Others disagree. But that is for a different post, probably on a different blog. Here I have a different peeve.
where m is the mass and c is the speed of light.
The above is common usage, but I have been noticing a different form:
E = m c2Where did that capital letter come from? It’s not the start of a new sentence! And the where clause isn’t a well-formed sentence, anyway!!
Where m is the mass and c is the speed of light.
Personally, I blame MSWord and the like, that oh so helpfully auto‘correct’ words that start a new line to start with a capital letter. (Yes, I know this can be switched off: I have switched it off. But many people don’t know, and haven’t.)
I have been patiently (most of the time, anyway) correcting my students when they do this. But now I have noticed people doing it in LaTeX documents, which (probably) means they are doing it deliberately.
As Bob the Angry Flower would say: No! Wrong! Totally Wrong! Stop doing it!