[Tex/LaTex] Writing Pseudocode in LaTeX

algorithmicxalgorithmscaptionserrors

I cannot seem to get any of the LaTeX pseudocode packages to work correctly on my computer. For example, if I run this block of code:

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

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

\end{document}

I get the following error message:

./pseudocode.tex:7: LaTeX Error: \caption outside float.

l.7 \caption {Euclid’s algorithm}\label{euclid}

Edit: I have tried loading the caption.sty package directly but with no success. Here is the .log file as requested.

> This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012)
> (format=pdflatex 2012.6.30)  11 SEP 2012 16:36 entering extended mode 
> restricted \write18 enabled.  file:line:error style messages enabled. 
> %&-line parsing enabled.
> **pseudocode.tex (./pseudocode.tex LaTeX2e <2011/06/27> Babel <v3.8m> and hyphenation patterns for english, dumylang, nohyphenation, ge
> rman-x-2012-05-30, ngerman-x-2012-05-30, afrikaans, ancientgreek,
> ibycus, arabi c, armenian, basque, bulgarian, catalan, pinyin, coptic,
> croatian, czech, danis h, dutch, ukenglish, usenglishmax, esperanto,
> estonian, ethiopic, farsi, finnis h, french, friulan, galician,
> german, ngerman, swissgerman, monogreek, greek, h ungarian, icelandic,
> assamese, bengali, gujarati, hindi, kannada, malayalam, ma rathi,
> oriya, panjabi, tamil, telugu, indonesian, interlingua, irish,
> italian,  kurmanji, latin, latvian, lithuanian, mongolian,
> mongolianlmc, bokmal, nynorsk,  polish, portuguese, romanian, romansh,
> russian, sanskrit, serbian, serbianc, s lovak, slovenian, spanish,
> swedish, turkish, turkmen, ukrainian, uppersorbian,  welsh, loaded.
> (/usr/local/texlive/2012/texmf-dist/tex/latex/base/article.cls
> Document Class: article 2007/10/19 v1.4h Standard LaTeX document class
> (/usr/local/texlive/2012/texmf-dist/tex/latex/base/size10.clo File:
> size10.clo 2007/10/19 v1.4h Standard LaTeX file (size option) )
> \c@part=\count79 \c@section=\count80 \c@subsection=\count81
> \c@subsubsection=\count82 \c@paragraph=\count83
> \c@subparagraph=\count84 \c@figure=\count85 \c@table=\count86
> \abovecaptionskip=\skip41 \belowcaptionskip=\skip42
> \bibindent=\dimen102 ) (./algorithm.sty \c@algorithm=\count87
> \Blockindent=\skip43 \algorithmindent=\skip44 ) (./algpseudocode.sty
> Package: algpseudocode 
> 
> (/usr/local/texlive/2012/texmf-dist/tex/latex/base/ifthen.sty Package:
> ifthen 2001/05/26 v1.1c Standard LaTeX ifthen package (DPC) )
> (/usr/local/texlive/2012/texmf-dist/tex/latex/algorithmicx/algorithmicx.sty
> Package: algorithmicx 2005/04/27 v1.2 Algorithmicx
> 
> Document Style algorithmicx 1.2 - a greatly improved `algorithmic'
> style \c@ALG@line=\count88 \c@ALG@rem=\count89 \c@ALG@nested=\count90
> \ALG@tlm=\skip45 \ALG@thistlm=\skip46 \c@ALG@Lnr=\count91
> \c@ALG@blocknr=\count92 \c@ALG@storecount=\count93
> \c@ALG@tmpcounter=\count94 \ALG@tmplength=\skip47 ) Document Style -
> pseudocode environments for use with the `algorithmicx' style )
> (./pseudocode.aux) \openout1 = `pseudocode.aux'.
> 
> LaTeX Font Info:    Checking defaults for OML/cmm/m/it on input line
> 5. LaTeX Font Info:    ... okay on input line 5. LaTeX Font Info:    Checking defaults for T1/cmr/m/n on input line 5. LaTeX Font Info:   
> ... okay on input line 5. LaTeX Font Info:    Checking defaults for
> OT1/cmr/m/n on input line 5. LaTeX Font Info:    ... okay on input
> line 5. LaTeX Font Info:    Checking defaults for OMS/cmsy/m/n on
> input line 5. LaTeX Font Info:    ... okay on input line 5. LaTeX Font
> Info:    Checking defaults for OMX/cmex/m/n on input line 5. LaTeX
> Font Info:    ... okay on input line 5. LaTeX Font Info:    Checking
> defaults for U/cmr/m/n on input line 5. LaTeX Font Info:    ... okay
> on input line 5.
> 
> 
> ./pseudocode.tex:7: LaTeX Error: \caption outside float.
> 
> See the LaTeX manual or LaTeX Companion for explanation. Type  H
> <return>  for immediate help.  ...                                    
> 
>                                                    l.7 \caption
>             {Euclid�s algorithm}\label{euclid} ?  ./pseudocode.tex:7: Emergency stop.  ...                                              
>                                                    l.7 \caption
>             {Euclid�s algorithm}\label{euclid} You're in trouble here.  Try typing  <return>  to proceed. If that doesn't work, type  X
> <return>  to quit.
> 
>   Here is how much of TeX's memory you used:  735 strings out of
> 493488  9692 string characters out of 3141326  56474 words of memory
> out of 3000000  4115 multiletter control sequences out of 15000+200000
> 4294 words of font info for 16 fonts, out of 3000000 for 9000  957
> hyphenation exceptions out of 8191  27i,0n,18p,256b,102s stack
> positions out of 5000i,500n,10000p,200000b,50000s ./pseudocode.tex:7: 
> ==> Fatal error occurred, no output PDF file produced!

Best Answer

Delete algorithm.sty and algpseudocode.sty from your working folder and recompile. This should allow LaTeX to find the correct versions in your TeX Directory Structure/TDS. In the very least, algorithm.sty should load the float package, which your "local version" does not...

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}

Best Answer

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