Stacking expressions
Formulas may become complex: we might need to put one symbol above another one or above whole expressions, or we wish to put lines, braces, or dots above symbols. There are several ways.
Underlining and overlining
\overline
puts a line above its argument, which may be nested:
s = \overline{AB}
The counterpart is \underline.
It doesn't have to be a line; braces are popular too. The commands are \underbrace
and \overbrace
.
You may use subscripts and superscripts:
N = \underbrace{1 + 1 + \cdots + 1}_n
Setting accents
We've already seen accents in text mode. For the math mode, we need different commands. They may be applied to any letter. Here's the list of math accents using the lowercase letter 'a' as an example:
The extensible ones are also called wide accents ; they try to fit the width of their argument.
Putting a symbol above another
Besides the array environment, there are amsmath commands to directly stack expressions:
\underset{expression below}{expression}puts an expression...
