5

This is the code I have:

    \begin{align}
     \vec{l} \cdot \vec{n} & = \left \langle 1,2,3 \right \rangle$ \cdot \left \langle                  3,-3,1 \right \rangle \\
                           & = 3 - 6 + 3 \\
                           & = 0 \\
     \end{align}

Now for some reason, I keep getting this message:

 "Missing } inserted <inserted text> } \end{align}"

I clearly have completed my }.

David Carlisle
  • 757,742
Lemon
  • 3,153

1 Answers1

11

You have \rangle$; simply delete the dollar sign. In your example, you don't really need \left and \right, so you can just say:

\documentclass{article} 
\usepackage{amsmath}

\begin{document}

\begin{align}
\vec{l} \cdot \vec{n} & = \langle 1,2,3 \rangle \cdot \langle 3,-3,1 \rangle \\
& = 3 - 6 + 3 \\
& = 0
\end{align}

\end{document}

enter image description here

Moriambar
  • 11,466
Gonzalo Medina
  • 505,128
  • 2
    Thanks, but why doesn't TeX POINT that out? Instead of giving me misleading errors? – Lemon May 13 '12 at 17:28
  • Wait why don't a need \left and \right? – Lemon May 13 '12 at 17:28
  • 3
    @jak To your first question: when you get the error message, type h; then you'll get the message "I've inserted something that you may have forgotten. (See the above.) With luck, this will get me unwedged. But if you really didn't forget anything, try typing 2' now; then my insertion and my current dilemma will both disappear." Now type 2 and you'll get <recently read> $. So, in fact, TeX sees the problem ;-) (not as quickly as you've expected, but it sees it). – Gonzalo Medina May 13 '12 at 17:33
  • @jak to your second question: in this particular case there's no need for stretchable delimiters since the involved inner expressions do not extend vertically beyond the standard characters height. – Gonzalo Medina May 13 '12 at 17:35
  • @above what that does that mean lol? stretchable delimiters...? So when do I need it? – Lemon May 13 '12 at 17:36
  • @jak stretchable delimiters will automatically adjust their (vertical) size according to the vertical size of the expression being delimited. In some circumstances you will require to use them, but in most cases you can use the alternative \bigX, \BigX, \biggX, and \BiggX family of commands. Search this site for questions about \left, \right and you'll find some discussions about whether and when to use them. – Gonzalo Medina May 13 '12 at 17:40