Replicate pseudocode format

Question

I have to include algorithms in a paper and they must appear as follows:

[A]     X ← X-1
        Y ← Y+1
        IF X ≠ 0 GOTO A

so I am trying to replicate this exactly, exploring some new packages as well but unfortunately it seems I can't get the hang of it. I'm finding particularly difficult including the [A] label before the statement and then the space on the next line. Is there any formatting tip I can follow or any package I can include?

Edit: For the assignment part I would love to use the math mode, mostly because there are lots of math signs I have to include, as for the appearence it should really be rendered as shown above: the label on the left, if present and if not there should be a nice space and all the statements must be stacked and aligned.

@egreg if I used tabular there should be a line between the label and the statement, shouldn't it? I definitely don't want that. — haunted85, Jan 11 '13 at 15:55
@haunted85 Why? \begin{tabular}{@{}ll@{}} will give you the alignment you need. Also tabbing could be a possibility, as @guillem says. Can you add some more details? Should it use math mode for the "assignment parts"? What about the label? Should the whole thing be centered or flush left? — egreg, Jan 11 '13 at 15:57
@egreg sorry but I really am a noob when it comes to macros... I hope you don't mind if I ask how do I use your snippet when I want to insert a statement without label, making sure the proper space is left? — haunted85, Jan 11 '13 at 16:03

score 3 · Accepted Answer · edited Apr 01 '17 at 19:28

I'll make some assumptions about what you want.

The label is in text form
The second part of the line is in math mode
The whole thing should be flush left

So, let's try:

\documentclass{article}

\usepackage{array}

\newenvironment{algodesc}
  {\begin{flushleft}\begin{tabular}{@{} l @{\hspace{3em}} >{$}l<{$} @{}}}
  {\end{tabular}\end{flushleft}}

\newcommand{\algolabel}[1]{[#1]}
\newcommand{\keyw}[1]{\textup{#1}}
\newcommand{\goto}[1]{\textup{GOTO #1}}

\begin{document}

Some text before the algorithm, explaining what it does
and then the algorithm itself:
\begin{algodesc}
\algolabel{A} & X \gets X-1 \\
              & Y \gets Y+1 \\
              & \keyw{IF}\ X\ne 0\ \goto{A}
\end{algodesc}
and some text after it.

\end{document}

Language keywords can be used in the argument of \keyw; the special one "GOTO" is in \goto that takes the label as argument.

You can also consider specialized package such as algpseudocode.

enter image description here

Yes, thank you so much for your help! :) If you are willing and have time, will you please explain what you have put in the \newenvironment part? — haunted85, Jan 11 '13 at 16:23

Replicate pseudocode format

1 Answers1