How to create an unnumbered algorithm with a caption?

Question

I want to do something like:

\begin{algorithm*}
\caption{My unnumbered algorithm}
% etc. etc.
\end{algorithm*}

or

\begin{algorithm}
\nonumbercaption{My unnumbered algorithm}
% etc. etc.
\end{algorithm}

Of course, the above is not LaTeX, just wishful thinking. What can I do to get an unnumbered algorithm with a caption?

Actually, the specific motivation is that I've split an algorithm in the middle since it's too long (using algorithmicx's \algstore); I want the second part to have a caption saying it's the second part, but I don't want it to have a new algorithm number.

Answer 1

If I understand your question correctly, you could use the \caption* command from the caption package to typeset the caption without label; a little example:

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

\begin{document}
\begin{algorithm}
  \caption{A test algorithm (Part I)}
  \begin{algorithmic}[1]
  \Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
  \ForAll {$v \in V(G)$}
  \State $l(v) \leftarrow \infty$
  \EndFor
  \algstore{bkbreak}
  \end{algorithmic}
\end{algorithm}

\begin{algorithm}
  \caption*{A test algorithm (Part II)}
  \begin{algorithmic}[1]
  \algrestore{bkbreak}
  \State $p(i) \leftarrow v_j$
  \State $l’(i) \leftarrow min$
  \State $changed \leftarrow l \not= l’$
  \EndProcedure
  \end{algorithmic}
\end{algorithm}

\end{document}

Answer 2

I suggest using the \ContinuedFloat command from the caption package instead and marking the second part as "continued":

\documentclass{article}

\usepackage{algorithm}
\usepackage{algpseudocode}
\usepackage{caption}

\begin{document}

\begin{algorithm}
  \caption{Test}
  \begin{algorithmic}
    \State $i \gets 42$
    \algstore{test}
  \end{algorithmic}
\end{algorithm}

\begin{algorithm}
  \ContinuedFloat
  \caption{Test (cont.)}
  \begin{algorithmic}
    \algrestore{test}
    \State $j \gets 24$
  \end{algorithmic}
\end{algorithm}

\end{document}

See the caption manual if you want the label, not caption, text to hold the "(continued)" word.

Answer 3

To follow on @Gonzalo's answer, I would duplicate the caption of the second (continued) part of the algorithm in full (using \caption*). Credit to him for the answer:

\documentclass{article}
\usepackage{caption}% http://ctan.org/pkg/caption
\usepackage{algorithm}% http://ctan.org/pkg/algorithm
\usepackage{algpseudocode}% http://ctan.org/pkg/algorithmicx

\begin{document}
\begin{algorithm}
  \caption{BellmanKalaba algorithm} \label{alg:first}
  \begin{algorithmic}[1]
  \Procedure {BellmanKalaba}{$G$, $u$, $l$, $p$}
  \ForAll {$v \in V(G)$}
  \State $l(v) \leftarrow \infty$
  \EndFor
  \algstore{bkbreak}
  \end{algorithmic}
\end{algorithm}

\begin{algorithm}
  \caption*{\textbf{Algorithm~\ref{alg:first}}\ BellmanKalaba algorithm (continued)}
  \begin{algorithmic}[1]
  \algrestore{bkbreak}
  \State $p(i) \leftarrow v_j$
  \State $l’(i) \leftarrow min$
  \State $changed \leftarrow l \not= l’$
  \EndProcedure
  \end{algorithmic}
\end{algorithm}
\end{document}

With a little work it would probably be possible to supply modify \caption so that an additional argument to \caption* could be the previous algorithm label, so as to produce the above result automatically.