[Tex/LaTex] How to have a “repeat” statement without an “until” statement using algorithmicx package

algorithmicx

I'd like to write something very similar to the algorithm shown below, but using the algorithmicx package. (This example comes from p. 152 of the book Proximal Algorithms by Boyd and Parikh.) How can I have a "repeat" statement without a corresponding "until" statement using algorithmicx?

(I mention the algorithmicx package specifically because I think it's more customizable than other algorithm packages.)

Best Answer

Here's one option using \algblockdefx to define a block and then \algonotext to suppress typesetting the ending part for the block:

\documentclass{article}
\usepackage{algorithmicx,algpseudocode}

\algblockdefx{MRepeat}{EndRepeat}{\textbf{repeat}}{}
\algnotext{EndRepeat}

\begin{document}

\begin{algorithmic}[1]
\State $sum\gets 0$
\State $i\gets 1$
\MRepeat
\State $sum\gets sum+i$
\State $i\gets i+1$
\EndRepeat
\State $i\gets 100$
\end{algorithmic}

\end{document}

Related Solutions

[Tex/LaTex] Algorithm with Latex ( Package algorithmicx)

You could simply do this:

\documentclass{article}
\usepackage{algorithm} %ctan.org\pkg\algorithms
\usepackage{algpseudocode}
\begin{document}

\begin{algorithm}
 \begin{algorithmic}[1]
 \Procedure{Euclid}{$a,b$}
 \State $r\gets a\bmod b$
 \While{$r\not=0$}
 \State $a\gets b$
 \State $b\gets r$
 \State $r\gets a\bmod b$
 \EndWhile
 \State \textbf{return} $b$ \Comment{The gcd is b}
 \EndProcedure
 \end{algorithmic}
 \caption{Euclid's algorithm}
 \label{euclid}
\end{algorithm}

\end{document}

Some packages define these kinds of floating environments, like alg, but that conflicted also.

[Tex/LaTex] Algorithm as figure and without italic and bold formatting

Is this what you are trying to achieve?

enter image description here

This is the MWE:

\documentclass{article}
\usepackage[plain]{algorithm}
\usepackage{algpascal}

\begin{document}

\algrenewcommand\textkeyword{\textrm}
\algdef{SE}{For}{End}[2]{%
  \textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
  \textkeyword{end}}

\begin{algorithm}
\begin{algorithmic}[1]
\State Assign an ordering $A_{1}, ..., A_{n}$ to the nonterminals of the grammar.
\For{i = 1}{n}
    \For{j = 1}{i-1}
    \State for each production of the form $A_{i} \rightarrow A_{j} \alpha$
    \End
\End
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}

\end{document}

Explanation

To match your first two requests, I've redefined the behavior of for to have an end statement by adding the lines:

\algdef{SE}{For}{End}[2]{%
  \textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
  \textkeyword{end}}

To match your last request, it suffices to add the line:
```
\algrenewcommand\textkeyword{\textrm}
```
which redefines the font for keywords to be \textrm instead of \textbf.
In regards of your 3rd request, there are two ways.
- If you want the algorithm to behave as an algorithm, simply load the algorithm package with the option plain as in the above MWE:
```
\usepackage[plain]{algorithm}
```
- If you want the algorithm to behave as a figure, there is no need to load the algorithm package, simply insert the algorithmic environment inside a figure, i.e. replace the lines
```
\begin{algorithm}
\begin{algorithmic}[1]
...
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}
```
  with
```
\begin{figure}
\begin{algorithmic}[1]
...
\end{algorithmic}
\caption{Paull's algorithm}
\end{figure}
```
  and you will have

Addendum

This is the complete implementation of the algorithm in the figure:

\documentclass{article}
\usepackage[plain]{algorithm}
\usepackage{algpascal}

\begin{document}

\algrenewcommand\textkeyword{\textrm}
\algdef{SE}{For}{End}[2]{%
  \textkeyword{for} \(#1\) \textkeyword{to} \(#2\) \textkeyword{do begin}}{%
  \textkeyword{end}}
\algdef{SE}{ForEach}{End}[1]{%
  \textkeyword{for each} #1 \textkeyword{do begin}}{%
  \textkeyword{end}}

\begin{algorithm}
\begin{algorithmic}[1]
\State Assign an ordering $A_{1}, \dots, A_{n}$ to the nonterminals of the grammar.
\For{i := 1}{n}
    \For{j := 1}{i-1}
        \ForEach{production of the form $A_{i} \rightarrow A_{j} \alpha$}
            \State remove $A_{i} \rightarrow A_{j} \alpha$ from the grammar
            \ForEach{production of the form $A_{j} \rightarrow \beta$}
                \State add $A_{i} \rightarrow \beta\alpha$ to the grammar
            \End
        \End
    \End
    \State transform the $A_{i}$-productions to eliminate direct left recursion
\End
\end{algorithmic}
\caption{Paull's algorithm}
\end{algorithm}

\end{document}

enter image description here

There is the need to define a new command \ForEach:

\algdef{SE}{ForEach}{End}[1]{%
  \textkeyword{for each} #1 \textkeyword{do begin}}{%
  \textkeyword{end}}

Note that I've defined \ForEach so to take one "text" argument, because it seemed to me the best way to define it.

If you want it to take a "math" argument, then define it as

\algdef{SE}{ForEach}{End}[1]{%
  \textkeyword{for each} \(#1\) \textkeyword{do begin}}{%
  \textkeyword{end}}

and use it as follows (amsmath is needed for the command \text):

\ForEach{\text{production of the form }A_{i} \rightarrow A_{j} \alpha}