The following is a piece of LaTeX code displaying a function. But in the PDF file generated , the right bracket "]", which is last thing in the equation, does not show up. However, if I replace "\right]" with just "]", then the right bracket show up. But I want the larger right bracket "\right]", not the small one "]". This code has another problem: the two fractions have different sizes! The first fraction is taller and the second fraction is shorter. The second fraction turns out to have smaller font size on the PDF, which I do not like.

Could anyone please point out to me how I can insert a large right bracket and have all the fractions use the same font size as those non-fractions (i.e. fractions should be twice the height as those non-fraction numbers)?

$\textbf{E} = E_0 \left[\frac{1}{\sqrt{2}} \textbf{\hat{x}} cos(kz-\omega t) + \frac{i}{\sqrt{2}} \textbf{\hat{y}} cos\left(kz-\omega t+\frac{\pi}{2}\right)\right]$

enter image description here

  • Works for me (except I had to replace \textbf with \mathbf around the \hats). What LaTeX distribution are you using? Perhaps something is wrong with it?
    – jjlin
    Sep 10, 2012 at 5:16
  • If you use \cos (instead of without the slash) it's treated as a proper function name, not three variables named c, o, and s. Sep 10, 2012 at 5:36
  • 1
    You do also realize that cos(x + pi/2) = -sin(x)? :) Sep 10, 2012 at 5:36
  • Change all the \textbf to \bf, then the right ] will show up and the second fraction will be in display mode rather than text mode.
    – ex-officemate of test
    Sep 11, 2012 at 4:25
  • 2
    That input produces many syntax errors and the missing bracket is a by-product of them. Don't overlook error messages from the compiler.
    – egreg
    Sep 11, 2012 at 8:39

1 Answer 1


You probably want

$\mathbf{E} = E_0 \bigl[\frac{1}{\sqrt{2}} \mathbf{\hat{x}} \cos(kz-\omega t)
  + \frac{i}{\sqrt{2}} \mathbf{\hat{y}} \cos(kz-\omega t+\frac{\pi}{2})\bigr]$

For getting a variable in boldface the correct way is to say \mathbf (which works also with accents such as \hat).

Instead of \bigl[ and \bigr] you can say \left[ and \right], it depends on personal taste: I feel that the latter gives too high brackets.

For the "cosine function" the right input is \cos.

  • is there a reason that \bigr[ and \bigl] are opposite to what one would expect? Sep 17, 2012 at 17:37
  • @barbarabeeton A mistake? :)
    – egreg
    Sep 17, 2012 at 17:58

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