# Adding curly brace to the right-hand side of the equation

I want to add brackets on one side of the equation and write something adjacent to it. But, I'm getting those words in the line below while I need those at one side of the equation. Can anyone help ?

$$w_t(t-1)=E_{t-1}P_t={}_{t-1}P_{t}^e=(1-\zeta )E(P_t|I_{t-1})+\zeta P_{t-1},0\leq \zeta \leq1$$
$$w_t(t-2)=E_{t-2}P_t={}_{t-2}P_{t}^e=(1-\zeta )E(P_t|I_{t-2})+\zeta P_{t-2},0\leq \zeta \leq 1$$
\raisebox{\depth}{$\Bigr\}\scriptstyle Difference in the information set in the 2 contracts$}


It's looking something like this, but I wanted the words and bracket to be at right side of both the equations.

I'm attaching for the same.

Maybe rcases?

\documentclass{article}
\usepackage{mathtools}
\begin{document}

$\begin{rcases} \begin{array}{r@{}l} w_t(t-1)&=E_{t-1}P_t={}_{t-1}P_{t}^e\\ &=(1-\zeta )E(P_t|I_{t-1})+\zeta P_{t-1}, \end{array} &0\leq \zeta \leq1\\ \begin{array}{r@{}l} w_t(t-2)&=E_{t-2}P_t={}_{t-2}P_{t}^e\\ &=(1-\zeta )E(P_t|I_{t-2})+\zeta P_{t-2}, \end{array} & 0\leq \zeta \leq 1 \end{rcases}\begin{array}{l} \text{Difference in the}\\ \text{information set in}\\ \text{the 2 contracts} \end{array}$
\end{document}


• Upvote for suggesting "rcases"...(it is new for me too... :-) ) – MadyYuvi May 27 at 4:58
• If you used tabular instead of array, the \text “wrappers” wouldn’t be needed. :-) – Mico May 27 at 4:59
• Really new concept, Thanks a lot! – Henam May 27 at 5:12

Some details of math typesetting are very important. For instance in

{}_{t-1}P_{t}^e


the “left subscript” would not descend as much as the “right subscript”. Some tricks are useful to achieve uniform appearance (mostly phantom superscripts).

Also the terms in the left-hand side should have lowered subscripts to match the others.

Spacing around = can be achieved with aligned, rather than array. The vertical bar should be \mid rather than |.

I use rcases wrapped around with a new environment that takes as arguments a clearance (optional, default 2em, meaning that at least half this clearance will appear at either side (useful if the left part is short, set it to a higher value) and the text that should appear to the right.

The text is typeset in a varwidth box with its maximum horizontal size determined by the width of the left part and the clearance.

\documentclass{article}
\usepackage{mathtools}
\usepackage{varwidth}

\usepackage{showframe} % just for the example

\newsavebox{\casesdescbox}
\newlength{\casesdescclearance}
\newenvironment{casesdesc}[2][2em]
{%
\setlength{\casesdescclearance}{#1}%
\newcommand{\casesdescdesc}{#2}%
\begin{lrbox}{\casesdescbox}
$\begin{rcases} } {% \end{rcases}\,$
\end{lrbox}%
\usebox{\casesdescbox}%
\begin{varwidth}{\dimexpr\displaywidth-\wd\casesdescbox-\casesdescclearance}
\raggedright\casesdescdesc
\end{varwidth}%
}

\begin{document}

\begin{casesdesc}{Difference in the information set in the two contracts} \begin{aligned}[b] w_t(t-1)&=E^{}_{t-1}P^{}_t={\vphantom{P}}^{}_{t-1}P_{t}^e\\ &=(1-\zeta )E(P_t \mid I_{t-1})+\zeta P_{t-1}, \end{aligned} & 0\leq \zeta \leq1 \\ \begin{aligned}[b] w_t(t-2) &=E^{}_{t-2}P^{}_t={\vphantom{P}}^{}_{t-2}P_{t}^e\\ &=(1-\zeta )E(P_t \mid I_{t-2})+\zeta P_{t-2}, \end{aligned} & 0\leq \zeta \leq 1 \end{casesdesc}

\begin{casesdesc}[4em]{\small Difference in the information set in the two contracts} \begin{aligned}[b] w_t(t-1)&=E^{}_{t-1}P^{}_t={\vphantom{P}}^{}_{t-1}P_{t}^e\\ &=(1-\zeta )E(P_t \mid I_{t-1})+\zeta P_{t-1}, \end{aligned} & 0\leq \zeta \leq1 \\ \begin{aligned}[b] w_t(t-2) &=E^{}_{t-2}P^{}_t={\vphantom{P}}^{}_{t-2}P_{t}^e\\ &=(1-\zeta )E(P_t \mid I_{t-2})+\zeta P_{t-2}, \end{aligned} & 0\leq \zeta \leq 1 \end{casesdesc}

\end{document}


I show two example typesetting, one with smaller text size for the description and wider clearance.

The showframe package is used just to show the margins of the text block.