6

The following is the piece of code that was working right before I made a few small minor changes. 

\begin{align}
\langle \prod_{i=1}^{n} \delta_i ^{n_i} y^{m_i}_i  \rangle 
= \sum _ {a_{i=1...n} = 0}^{n_{i=1...n}}   
  \sum_{b_{i=1...n} = 0} ^{m_{i=1...n}}     
  \prod_{i=1}^{n} \left [ ^{n_i}C_{a_i} ( \sum _ {\rho_{\{a_{1\leq i \leq n}\}}}   
  \prod _{B \in \rho_{\{ a_{1 \leq i \leq n} \}} 
  \langle \delta_i ^{\vert B \vert} \rangle _c ) ^{m_i}C_{b_i} 
  ( \sum _ {\rho_{\{b_{1\leq i\leq n}\}}} 
  \prod _{B \in \rho_{\{b_{1\leq i \leq n} \}}} 
  \langle y_i ^{\vert B \vert} \rangle_c ) \right ] \langle 
  \prod_{i=1}^{n} \delta_i ^{n_i - a_i} y_i ^{m_i - b_i} \rangle _{nzl}
\end{align}
  • Also can I get the innermost pair of $( )$ brackets to be large using \left and \right?
Przemysław Scherwentke
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user6818
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1 Answers1

3

You're missing a closing curly brace to delimit the subscript of the third \prod expression.

In the code below, I've also (i) inserted a line break, (ii) increased the sizes of some of the fences, and (iii) replaced ... with ,\dots,. Note that the size of the fences is deliberately set so as not to span the subscripts and superscripts of the sum and product symbols.

enter image description here

\documentclass{article}
\usepackage{amsmath}
\usepackage[margin=1in]{geometry} % use whatever page margins are right for you
\begin{document}
\begin{align}
\biggl\langle \prod_{i=1}^{n} \delta_i ^{n_i} y^{m_i}_i \biggr\rangle 
 &= 
\sum _ {a_{i=1,\dots, n} = 0}^{n_{i=1,\dots, n}} 
\sum_{b_{i=1,\dots, n} = 0} ^{m_{i=1,\dots, n}} 
\prod_{i=1}^{n} \Bigg[
  {}^{n_i}C_{a_i} \biggl(
    \sum _ {\rho_{\{a_{1\leq i \leq n}\}}} 
    \prod _{B \in \rho_{\{ a_{1 \leq i \leq n} \}}} 
    \bigl\langle \delta_i ^{\vert B \vert} \bigr\rangle _c 
  \biggr) ^{m_i}\notag\\ 
 &\quad \times C_{b_i}
  \biggr( \sum _ {\rho_{\{b_{1\leq i\leq n}\}}} 
    \prod _{B \in \rho_{\{b_{1\leq i \leq n} \}}} 
    \langle y_i ^{\lvert B \rvert} \rangle_c 
  \biggr) \Bigg] 
  \biggl\langle 
    \prod_{i=1}^{n} \delta_i ^{n_i - a_i} y_i ^{m_i - b_i} 
  \biggr\rangle _{\text{nzl}}
\end{align} 
\end{document}
Mico
  • 506,678
  • Thanks for this huge effort! I have never seen these commands of \bigr, \bigl, \Bigg, \biggr, \biggl. You are saying that these are somehow better than the \left and \right that I use? How do you actually decide what to use? – user6818 Jul 21 '13 at 19:42
  • @user6818 - You're welcome. There are (at least) two reasons for not using \left and \right to size the fences, and for using explicit size instructions (\big, \Big, \bigg, and \Bigg) instead: (i) The fences straddle a line break, as is the case with the square brackets in your example. (ii) The fences would be too big if sized automatically, as would be the case for the round parentheses and angle brackets in your example. For fences that surround display-style sum and product symbols, Knuth recommends the \bigg[lr] sizing instruction. – Mico Jul 21 '13 at 22:31