How is it able to center a single line in an align?
I want to center 0 = 0.
MWE:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align*}
0 = 0\\
a &= b & c &= d\\
a &= b & c &= d\\
a &= b & c &= d\\
a &= b & c &= d
\end{align*}
\end{document}
To have more or less the spacing of the original code, I'd use the alignedat environment, to have full control on the spacing:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{gather*}
0 = 0\\
\begin{alignedat}{2}
a &= b &\hspace{10em} c &= d\\
a &= b & c &= d\\
a &= b & c &= d\\
a &= b & c &= d
\end{alignedat}
\end{gather*}
\end{document}
0=0 with a more equations -0=0, ...?
aligned environment.
10em freely? AMS splits the hole free horizontal space around and in-between the equations equally, doesn't it?
&\hspace{10em}c denotes the l.h.s. of the 2nd column of alignment. This l.h.s. is right-aligned w.r.t. the following &=.
alignedat is just an aligned with zero space between the equations, right?
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{gather*}
0 = 0\\
\begin{aligned}
a &= b & c &= d\\
a &= b & c &= d\\
a &= b & c &= d\\
a &= b & c &= d
\end{aligned}
\end{gather*}
\end{document}
alignedtogether withgather*.gather*andaligned, although only a single "column" is aligned. This might not be an obvious help to you, but it might help some future person loolking for information.