algorithm2e with 'ruled' but with caption underneath?

Question

I would like to present an algorithm in my article. For that I am using the algorithm2e package (and I have used it for many years).

I want to use the ruled option, i.e., I load the package like this:

\usepackage[ruled,noend,noline,slide]{algorithm2e}

Unfortunately, with the ruled option, the algorithm2e package puts the caption above the pseudo code.

However, I want the caption to appear underneath the pseudo-code, just like any other caption in figures or tables.

Does anybody know, what I need to change in the style file to make this possible? Or can I achieve it with the help of the float package? (Note that I still would like to have a kind of algorithmic environment like this

\begin{myalgorithm}[tb]
\If{...}
\caption{An algorithm}
\end{myalgorithm}

) I am using the latest version, i.e., 4.01, of algorithm2e.sty.

Answer 1

You can achieve this by defining a new environment which puts the caption under instead of the default top, and adjusting the vertical skip between a rule and the caption text:

\documentclass{book}
\usepackage[ruled,noend,noline,slide]{algorithm2e}

\makeatletter
\newenvironment{Ualgorithm}[1][htpb]
  {\def\@algocf@post@ruled{\kern\interspacealgoruled\hrule  height\algoheightrule\kern3pt\relax}%
    \def\@algocf@capt@ruled{under}
    \begin{algorithm}[#1]}
  {\end{algorithm}}
\makeatother

\begin{document}

\begin{algorithm}
\If{$i<5$}{some action}
\caption{A ruled algorithm with caption above}
\end{algorithm}

\begin{Ualgorithm}
\If{$i<5$}{some action}
\caption{A ruled algorithm with caption below}
\end{Ualgorithm}

\end{document}