[Tex/LaTex] How to define new loops in algorithmicx

algorithm2ealgorithmicalgorithmicxalgorithms

How can I define a new loop in algorithmicx? For example, code like this:

ex1)

PreLoop s do

–statement1

–statement2

ex2)

PostLoop s do

–statement1

–statement2

Is it possible to define it as a command?

Best Answer

Yes, this can be done using the \algdef command. This is an example:

\documentclass{article}
\usepackage{algpseudocode}
\algdef{SE}{PreLoop}{EndPreLoop}[1]{\textbf{preloop} \(\mbox{#1}\) \textbf{do}}{\textbf{end}}%

\begin{document}
\begin{algorithmic}[1]
\Procedure{Euclid}{$a,b$}\Comment{The g.c.d. of a and b}
\State $r\gets a\bmod b$
\PreLoop{$r\not=0$}\Comment{We have the answer if r is 0}
\State $a\gets b$
\State $b\gets r$
\State $r\gets a\bmod b$
\EndPreLoop\label{euclidendwhile}
\State \textbf{return} $b$\Comment{The gcd is b}
\EndProcedure
\end{algorithmic}

\end{document}

For more information, see the algorithmicx manual, e.g., http://mirror.unl.edu/ctan/macros/latex/contrib/algorithmicx/algorithmicx.pdf .

Related Solutions

[Tex/LaTex] How to define a new command in algorithmicx

In the documentation you can find \algnewcommand. In relation \Require is defined as

\algnewcommand\algorithmicrequire{\textbf{Require:}}

So you can do:

\algnewcommand\algorithmicinput{\textbf{INPUT:}}
\algnewcommand\INPUT{\item[\algorithmicinput]}

Here is a complete example:

\documentclass[a4paper,11pt]{article}
\usepackage{algorithmicx}
\usepackage{algorithm}
\usepackage{algpseudocode}
\algnewcommand\algorithmicinput{\textbf{INPUT:}}
\algnewcommand\INPUT{\item[\algorithmicinput]}
\begin{document}
\begin{algorithmic}[1]
\INPUT foo
\Require $x\ge5$
\Ensure $x\le-5$
\Statex
\While{$x>-5$}
\State $x\gets x-1$
\EndWhile
\end{algorithmic}
\end{document}

enter image description here

[Tex/LaTex] Switch cases in algorithmic

Use the following:

enter image description here

\documentclass{article}
\usepackage{algpseudocode}% http://ctan.org/pkg/algorithmicx
\begin{document}
% New definitions
\algnewcommand\algorithmicswitch{\textbf{switch}}
\algnewcommand\algorithmiccase{\textbf{case}}
\algnewcommand\algorithmicassert{\texttt{assert}}
\algnewcommand\Assert[1]{\State \algorithmicassert(#1)}%
% New "environments"
\algdef{SE}[SWITCH]{Switch}{EndSwitch}[1]{\algorithmicswitch\ #1\ \algorithmicdo}{\algorithmicend\ \algorithmicswitch}%
\algdef{SE}[CASE]{Case}{EndCase}[1]{\algorithmiccase\ #1}{\algorithmicend\ \algorithmiccase}%
\algtext*{EndSwitch}%
\algtext*{EndCase}%

\begin{algorithmic}[1]
  \Switch{$s$}
    \Case{$a$}
      \Assert{0}
    \EndCase
    \Case{$b$}
      \Assert{1}
    \EndCase
  \EndSwitch
\end{algorithmic}
\end{document}

Both new "environments" \Switch...\EndSwitch and \Case...\EndCase are defined to have beginning and ending text. However, using \algnotext*{<env>} removes any typesetting of that command, effectively removing the ending command for both \Switch and \Case. It's still needed, since there may be more than one entry so its not possible to generalise with some number-of-lines-termination.

Best Answer

Related Solutions

[Tex/LaTex] How to define a new command in algorithmicx

[Tex/LaTex] Switch cases in algorithmic

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