cases

cases

[David Arnold]

All,

Try:

\documentclass[12pt]{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
  \label{func}
  P_{r-j}=
  \begin{cases}
    0, & \text{if $r-j$ is odd}\\
    r!(-1)^{(r-j)/2}, & \text{if $r-j$ is even.}
  \end{cases}
\end{equation}

\end{document}

Then try:

\usemodule[amsl]

\starttext

\placeformula[func]
\startformula
P_{r-j}=
\startcases
0, & \text{if $r-j$ is odd}\\
r!(-1)^{(r-j)/2}, & \text{if $r-j$ is even.}
\stopcases
\stopformula

\stoptext

You'll note that the spacing in the latter is not as good.