7

According to its documentation, algorithmicx package allows break up an algorithm inside a document, as follows:

Breaking up an algorithm with algorithmicx

Related tex code is:

\documentclass{article}
\usepackage{algorithm}
\usepackage{algpseudocode}
\begin{document}
\begin{algorithm}
\caption{Part 1}
\begin{algorithmic}[1]
\Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
\ForAll {$v \in V(G)$}
\State $l(v) \leftarrow \infty$
\EndFor
\State $l(u) \leftarrow 0$
\Repeat
\For {$i \leftarrow 1, n$}
\State $min \leftarrow l(v_i)$
\For {$j \leftarrow 1, n$}
\If {$min > e(v_i, v_j) + l(v_j)$}
\State $min \leftarrow e(v_i, v_j) + l(v_j)$
\State \Comment For some reason we need to break here!
\algstore{bkbreak}
\end{algorithmic}
\end{algorithm}
And we need to put some additional text between\dots
\begin{algorithm}[h]
\caption{Part 2}
\begin{algorithmic}[1]
\algrestore{bkbreak}
\State $p(i) \leftarrow v_j$
\EndIf
\EndFor
\State $l’(i) \leftarrow min$
\EndFor
\State $changed \leftarrow l \not= l’$
\State $l \leftarrow l’$
\Until{$\neg changed$}
\EndProcedure
\end{algorithmic}
\end{algorithm}
\end{document}

It's easy to note that the caption number is incremented between the two pieces of code (Algorithm 3 for the first, Algorithm 4 for the second). Moreover, is it possible to have the same number for both? If yes, how can I do that?

4
  • 3
    Just add \addtocounter{algorithm}{-1} before \caption{Part 2} (and don't use a label for this one, of course).
    – egreg
    Commented May 10, 2013 at 15:08
  • Just a simple trick but it works fine. Thank you so much.
    – vdenotaris
    Commented May 10, 2013 at 15:11
  • Related/duplicate: How to break a pseudocode box between two pages
    – Werner
    Commented May 10, 2013 at 15:22
  • 1
    @Werner related, yes. Duplicate, I think not. The other question deals with how to break algorithms, and this is a known fact for this questioner. In this case, the question is about how to prevent the counter from stepping, and this is not covered in the other answers. Commented May 10, 2013 at 15:26

2 Answers 2

8

As egreg has mentioned in a comment, one option would be to use

\addtocounter{algorithm}{-1} 

before \caption{Part 2}. Another option, not requiring manually changing counters and that additionally gives you the possibility to use a customized formatting for the continued algorithm, would be to use \ContinuedFloat from the caption package. An example with the default caption format for \ContinuedFloat:

\documentclass{article}
\usepackage{caption}
\usepackage{algorithm}
\usepackage{algpseudocode}
\begin{document}
\begin{algorithm}
\caption{Part 1}
\begin{algorithmic}[1]
\Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
\ForAll {$v \in V(G)$}
\State $l(v) \leftarrow \infty$
\EndFor
\State $l(u) \leftarrow 0$
\Repeat
\For {$i \leftarrow 1, n$}
\State $min \leftarrow l(v_i)$
\For {$j \leftarrow 1, n$}
\If {$min > e(v_i, v_j) + l(v_j)$}
\State $min \leftarrow e(v_i, v_j) + l(v_j)$
\State \Comment For some reason we need to break here!
\algstore{bkbreak}
\end{algorithmic}
\end{algorithm}
And we need to put some additional text between\dots
\begin{algorithm}[h]
\ContinuedFloat
\caption{Part 2}
\begin{algorithmic}[1]
\algrestore{bkbreak}
\State $p(i) \leftarrow v_j$
\EndIf
\EndFor
\State $l’(i) \leftarrow min$
\EndFor
\State $changed \leftarrow l \not= l’$
\State $l \leftarrow l’$
\Until{$\neg changed$}
\EndProcedure
\end{algorithmic}
\end{algorithm}
\end{document}

enter image description here

An an example with a modified format for the caption of continued floats:

\documentclass{article}
\usepackage{caption}
\usepackage{algorithm}
\usepackage{algpseudocode}

\makeatletter
\DeclareCaptionLabelFormat{algcontinued}{\ALG@name~#2 (Continued)}
\makeatother
\captionsetup[ContinuedFloat]{labelformat=algcontinued}

\begin{document}
\begin{algorithm}
\caption{Part 1}
\begin{algorithmic}[1]
\Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
\ForAll {$v \in V(G)$}
\State $l(v) \leftarrow \infty$
\EndFor
\State $l(u) \leftarrow 0$
\Repeat
\For {$i \leftarrow 1, n$}
\State $min \leftarrow l(v_i)$
\For {$j \leftarrow 1, n$}
\If {$min > e(v_i, v_j) + l(v_j)$}
\State $min \leftarrow e(v_i, v_j) + l(v_j)$
\State \Comment For some reason we need to break here!
\algstore{bkbreak}
\end{algorithmic}
\end{algorithm}
And we need to put some additional text between\dots
\begin{algorithm}[h]
\ContinuedFloat
\caption{Part 2}
\begin{algorithmic}[1]
\algrestore{bkbreak}
\State $p(i) \leftarrow v_j$
\EndIf
\EndFor
\State $l’(i) \leftarrow min$
\EndFor
\State $changed \leftarrow l \not= l’$
\State $l \leftarrow l’$
\Until{$\neg changed$}
\EndProcedure
\end{algorithmic}
\end{algorithm}
\end{document}

enter image description here

4

Adding \addtocounter{algorithm}{-1} before issuing the \caption command in the second algorithm environment solves the problem.

However, this (and also the \ContinuedFloat approach) will break hyperref linking mechanism, if this package is used.

\documentclass{article}
\usepackage{algorithm}
\usepackage{algpseudocode}

%\usepackage{hyperref}

%%% add the following two lines if hyperref is used
%\newcounter{Halgorithm}
%\floatevery{algorithm}{\stepcounter{Halgorithm}}

\begin{document}
\begin{algorithm}
\caption{Part 1}
\begin{algorithmic}[1]
\Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
\ForAll {$v \in V(G)$}
\State $l(v) \leftarrow \infty$
\EndFor
\State $l(u) \leftarrow 0$
\Repeat
\For {$i \leftarrow 1, n$}
\State $min \leftarrow l(v_i)$
\For {$j \leftarrow 1, n$}
\If {$min > e(v_i, v_j) + l(v_j)$}
\State $min \leftarrow e(v_i, v_j) + l(v_j)$
\State \Comment For some reason we need to break here!
\algstore{bkbreak}
\end{algorithmic}
\end{algorithm}
And we need to put some additional text between\dots
\begin{algorithm}
\addtocounter{algorithm}{-1}
\caption{Part 2}
\begin{algorithmic}[1]
\algrestore{bkbreak}
\State $p(i) \leftarrow v_j$
\EndIf
\EndFor
\State $l’(i) \leftarrow min$
\EndFor
\State $changed \leftarrow l \not= l’$
\State $l \leftarrow l’$
\Until{$\neg changed$}
\EndProcedure
\end{algorithmic}
\end{algorithm}
\end{document}

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