Alignat not working properly

Question

Consider this minimal example :

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}  

\begin{document}
\begin{alignat}{2}
&\frac{1}{2} log(\langle d_x, d_x \rangle + \frac{1}{2} log(\langle d_y, d_y \rangle - \log(\langle d_x, d_y \rangle) &> 0  \quad| \cdot 2 \\\nonumber
\Leftrightarrow \quad &log(\langle d_x, d_x \rangle + log(\langle d_y, d_y \rangle - 2 \log(\langle d_x, d_y \rangle) &> 0   \\\nonumber
\Leftrightarrow \quad &log(\langle d_x, d_x \rangle + log(\langle d_y, d_y \rangle  &>  2 \log(\langle d_x, d_y \rangle)   \\\nonumber
\Leftrightarrow \quad &e^{log(\langle d_x, d_x \rangle + log(\langle d_y, d_y \rangle}  &>  e^{2 \log(\langle d_x, d_y \rangle)}   \\\nonumber
\end{alignat}
\end{document}

I expect the start of the line as well as the > sign to be aligned. However only the start of the line is aligned and not the > sign. See this:

Screenshot

You need 2*2-1 &'s on each line, so you are missing the seperator & — daleif, May 12 '15 at 14:56
useful information at Difference between align and alignat environments. (possibly considered a dupe.) — barbara beeton, May 12 '15 at 16:43

score 5 · Accepted Answer · answered May 12 '15 at 14:59

You need to use more alignment operators & since the traditional output around these follow a Right-Left alignment:

enter image description here

\documentclass{article}
\usepackage{amsmath}  

\begin{document}
\begin{alignat*}{3}
  &\tfrac{1}{2} \log(\langle d_x, d_x \rangle + \tfrac{1}{2} \log(\langle d_y, d_y \rangle - \log(\langle d_x, d_y \rangle) &&> 0  \quad| \cdot 2 \\
  \Leftrightarrow \quad &\log(\langle d_x, d_x \rangle + \log(\langle d_y, d_y \rangle - 2 \log(\langle d_x, d_y \rangle) &&> 0 \\
  \Leftrightarrow \quad &\log(\langle d_x, d_x \rangle + \log(\langle d_y, d_y \rangle  &&>  2 \log(\langle d_x, d_y \rangle) \\
  \Leftrightarrow \quad &e^{\log(\langle d_x, d_x \rangle + \log(\langle d_y, d_y \rangle}  &&>  e^{2 \log(\langle d_x, d_y \rangle)}
\end{alignat*}
\end{document}

Note that you can use alignat* to avoid repetitive \nonumbers.

Alignat not working properly

1 Answers1