TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

The following TeX breaks rendering, but if I remove the \left function, the TeX renders (but without the stretchy brace). I'm helping a colleague and I'm too new to LaTeX and TeX to know how to approach fixing this.

\ \ \small{w_{1}[n] } = \left{ 
 1 & \ \ \small{n=0,1,...,12}\\
 0 & \ \ \text{otherwise} \\
share|improve this question
You are missing the matching \right. (an empty delimiter). Is this in a TeX document? – egreg Nov 26 '12 at 16:28

You wrote \left{ <stuff>. TeX is trying to make <stuff> into a left delimiter because { opens a group. You probably meant to write \left\{ <stuff>.

Moreover, you probably should just be using the cases environment from amsmath instead.

share|improve this answer
Combine your answer with the egreg's comment above to get the pretty perfect answer! ;-) – Paul Gaborit Nov 26 '12 at 17:03
I edited the TeX to this, but it still doesn't render. \small{w_{1}[n] } = \left\{ \begin{array}{ll} 1 \ \ \small{n=0,1,...,12}\\0 \ \ \text{otherwise} \\\ \end \right {array} – pwilkins Nov 26 '12 at 18:56
@pwilkins \right also needs to be followed by a delimiter, e.g., \right\}. If you don't want a right delimiter use \right. (including the dot!). – clemens Nov 26 '12 at 19:11
Bingo! That's turned the trick. The original TeX didn't have the trailing brace so the 'dot' fixed it. Here's my working version: $$ \small{w_{1}[n] } = \left\{ \begin{array}{ll} 1 \ \ \small{n=0,1,...,12}\\0 \ \ \text{otherwise} \\\ \end{array}\right. $$ – pwilkins Nov 26 '12 at 19:11

Your use of the \small directive when TeX is in math mode can't work. (Moreover, the command \small is a switch and doesn't take an argument.) I suggest that you set up the MWE as follows instead:

\[ % begin display math
w_{1}[n]  = 
   1 & n=0,1,\dots,12\\
   0 & \text{otherwise} \\
\] % end display math

enter image description here

share|improve this answer
I believe that the question refers only to MathJax; where \small has no effect, in my experiment. – egreg Nov 26 '12 at 23:52
@egreg - in TeX's math mode, executing \small won't have an effect either, right? – Mico Nov 27 '12 at 4:39
It issues a warning: `LaTeX Font Warning: Command \small invalid in math mode' – egreg Nov 27 '12 at 7:23

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

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