I was trying to typesset piecewise functions earlier and I had a problem typesseting only the left brace and not the right as it couldn't accept only \left\{. After that I tried adding \right but there were still errors. Until I found out this piece of code in wikipedia showing a dot after \right. What is the use of this dot?

\[f(x) = \left\{
    x^2 & : x < 0\\
    x^3 & : x \ge 0
  • Simply expressed: The dot fakes a closing 'bracket' when you opened a left one. Normally, LaTeX expects a right 'bracket', omitting it will lead to errors. The dot's job is to prevent this – user31729 Oct 13 '14 at 14:28
  • . has delimiter code 0 which means that it is a legal delimiter that can go after \left or \right it causes the horizontal space \nulldelimiterspace to be added and allows \left \right pairs to match. – David Carlisle Oct 13 '14 at 14:30

A \left\{ should always be matched with a \right\} in the same line. This will put the opening and closing braces both. In case if you want only the opening brace (\left\{) then you need to match it with an invisible \right. The . is for invisible pair. Same thing is true for \left. if you want only the closing pair.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.