23.  Big Brackets, Etc.

      To get big brackets [~], braces {~}, parentheses (~), and bars |~| around things, use the left and right commands: left { a over b + 1 right }
~=~ left ( c over d right )
+ left [ e right ]


The resulting brackets are made big enough to cover whatever they enclose. Other characters can be used besides these, but the are not likely to look very good. One exception is the floor and ceiling characters: left floor x over y right floor
<= left ceiling a over b right ceiling


      Several warnings about brackets are in order. First, braces are typically bigger than brackets and parentheses, because they are made up of three, five, seven, etc., pieces, while brackets can be made up of two, three, etc. Second, big left and right parentheses often look poor, because the character set is poorly designed.

      The right part may be omitted: a ``left something'' need not have a corresponding ``right something''. If the right part is omitted, put braces around the thing you want the left bracket to encompass. Otherwise, the resulting brackets may be too large.

      If you want to omit the left part, things are more complicated, because technically you can't have a right without a corresponding left. Instead you have to say left "" ..... right )
for example. The left "" means a ``left nothing''. This satisfies the rules without hurting your output.