[Tex/LaTex] Alignment in algorithmic environment

algorithmichorizontal alignmentmath-mode

I don't like how there is often a slight misalignment between assignment statements in an algorithmic environment. For example, the first version of the algorithm given below looks strange to me. I would like to be able to align the two statements, but the commented version in my example fails to even compile. I could always manually add some space to make things line up (see the last version below), but this is obviously not a good way to go about doing things for a number of reasons. Does anyone have a good way of making the assignment statements to line up?

\documentclass{article}
    \usepackage{algorithm}
    \usepackage{algorithmicx}
    \usepackage{amsmath}

\begin{document}

\begin{algorithm}
    \caption{Compute some stuff}
    \begin{algorithmic}
        \State \( x \gets 1 \)
        \State \( m \gets 2 \)
    \end{algorithmic}
\end{algorithm}

%\begin{algorithm}
%   \caption{Compute some stuff}
%   \begin{algorithmic}
%       \begin{align*}
%           x & \gets 1 \\
%           m & \gets 2
%       \end{align*}
%   \end{algorithmic}
%\end{algorithm}

\begin{algorithm}
    \caption{Compute some stuff}
    \begin{algorithmic}
        \State \( \hspace{3pt} x \gets 1 \)
        \State \( m \gets 2 \)
    \end{algorithmic}
\end{algorithm}

\end{document}

Best Answer

You need to use some "box manipulation":

enter image description here

\documentclass{article}
\usepackage{algorithm,algorithmicx}% http://ctan.org/pkg/{algorithms,algorithmicx}
\usepackage{mathtools}% http://ctan.org/pkg/mathtools

\begin{document}

\begin{algorithm}
    \caption{Compute some stuff}
    \begin{algorithmic}
        \State \( x \gets 1 \)
        \State \( m \gets 2 \)
    \end{algorithmic}
\end{algorithm}

\begin{algorithm}
    \caption{Compute some stuff}
    \begin{algorithmic}
        \State \( \phantom{m}\mathllap{x} \gets 1 \)
        \State \( m \gets 2 \)
    \end{algorithmic}
\end{algorithm}

\end{document}

I insert a box that has the width of the widest element (m in this case) using \phantom. This pushes the setting as deep is as necessary. Then I insert x using a left overlap (in math-mode; via \mathllap from mathtools). It takes up zero width, so it doesn't affect the spacing or "move the cursor" so to speak. The rest is set as usual.

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