%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 8-2-6 on page 472.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexamargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{183.0pt}
\StartShownPreambleCommands
\usepackage{amsmath}
\StopShownPreambleCommands
\begin{document}
\begin{multline}  \tag{2}
  \sum_{t \in \mathbf{T}} \int_a^t
    \biggl\lbrace \int_a^t f(t - x)^2 \,
            g(y)^2 \,dx \biggr\rbrace \,dy \\
  = \sum_{t \notin \mathbf{T}} \int_t^a
      \biggl\lbrace g(y)^2 \int_t^a
        f(x)^2 \,dx \biggr\rbrace \,dy
\end{multline}

\setlength\multlinegap{0pt}
\begin{multline}  \tag{2}
  \sum_{t \in \mathbf{T}} \int_a^t
    \biggl\lbrace \int_a^t f(t - x)^2 \,
            g(y)^2 \,dx \biggr\rbrace \,dy \\
  = \sum_{t \notin \mathbf{T}} \int_t^a
      \biggl\lbrace g(y)^2 \int_t^a
        f(x)^2 \,dx \biggr\rbrace \,dy
\end{multline}
\end{document}
