Match spacing of align in array environment

Question

To typeset some displayed equations, only the array environment was powerful enough. However, the spacing of the array environment doesn't match the spacing of the align environment.

How do I set the spacing of the array environment, such that equals the vertical spacing of the align environment.

For instance:

\begin{align*}
a & = b + c \\
d & = e + f
\end{align*}

and

\[\begin{array}{rl}
a & = b + c \\
d & = e + f
\end{array}\]

have different spacing.

Answer 1

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

\begin{document}

\begin{align*}
a & = b + c \\
d & = e + f
\end{align*}

\[
\begin{array}{rl}
a & = b + c \\
d & = e + f
\end{array}
\]

\arraycolsep=1.4pt
\def\arraystretch{1.2}
\[
\begin{array}{rl}
a & = b + c \\
d & = e + f
\end{array}
\]
\end{document}