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Equation:

\documentclass[12pt]{article}
\usepackage{mathtools}
\begin{document}
    \begin{eqnarray}
    \langle\pi_n|\hat{H}^{ab}|\pi_m\rangle & =& \Delta_{nm} g\int d^3x|\Psi_p(x-r_m)|^2\left\{|\phi_0(x)|^2+
    \sum_{q=1}^{N}\left[\hat{b}_q\left(a\phi_0^*(x)-a\phi_0(x)\right)\right.\right.\\
    & & +\left.\left. \phi*a*a*a-\phi^*_0(x)v^*_q(x)\right]\right\}
    \end{eqnarray}
\end{document}

The third bracket at the end of the equation is of different size than the earlier bracket used in the first line.

Ani
  • 21
  • Your example gives me errors about unbalanced brackets. Besides that, the wrong sizing might be caused by the line break you put in? – remco May 15 '18 at 05:59
  • 1
    Use manual scaling instead of automatic, that is use on on the big, Big, bigg or Bigg macros (usually a good idea to use them in their Xl and Xr variants. Also, don't use eqnarray, it's a very flawed construction, use the stuff from amsmath instead – daleif May 15 '18 at 05:59
  • I agree Remco, size varies because in the first line I have summation sign which is not there after the line break. But the question is, can I maintain the size using \left{ and \right} in these two lines, if possible? – Ani May 15 '18 at 06:21

1 Answers1

2

The solution is to follow the advice given by daleif and to use \Big contructs. I give an example below, avoiding the horrible use of eqnarray

\documentclass[12pt]{article}
\usepackage{mathtools}
\begin{document}
    \begin{equation}
    \begin{aligned}
   \langle \pi \dots \rangle  ={} &\Delta_{nm} g \dots \Biggl\{ \phi \dots \Bigl( \phi \\ 
  & + \phi \Bigr) \phi \Biggr\}
    \end{aligned}
    \end{equation}
\end{document}

The delimiters are on different lines but have the same size.

enter image description here

Denis
  • 5,267
  • Dear Denis, the use of left( and \right) is more suitable while writing an equation. I don't care about the size of summation, integration, fraction and differentiation etc. These bracket adjust itself in a single line. Whereas in case of \Big(, I have see back which big I have already used and which one I can use next. BTW remove the start from the \begin{eqaution*} and see the equation number where it appears in the multi-line equation. – Ani May 15 '18 at 06:52
  • it is better to use \Bigl on the left and \Bigr on the right and not use \Big. @Anilchauhan using \Bigl is the correct answer, even when not split over a line it is better to use the fixed size brackets rather than \left\right as the spacing is better (we have many answers on site showing the problems with left-right) – David Carlisle May 15 '18 at 06:56
  • You can use also \vphantom in order to get the same sized brackets and braces. – RockyRock May 15 '18 at 07:01
  • @DavidCarlisle Thanks for pointing out that it is better to use \bigland \bigr. I have modified the answer. Also added eqn number since the OP seems to want one. – Denis May 15 '18 at 07:02