[Tex/LaTex] \Fn ! Undefined control sequence

Question

Under Ubuntu 15.04, I want to use algorithm2e to write pseudo code, when I copied an example from the documentation, TeXStudio displays error indicating that the command \Fn is undefined. I thought that the package might be outdated so I run an update over texlive-science

sudo apt-get install texlive-science

but it shows that texlive-science is already the newest version.
Is it not updated in Ubuntu repositories? If so, how can I update algorithm2e to the lasted version?

Answer 1

You can find the required definition of \Fn in the algorithm2e documentation code. It's defined using \SetKwProg.

The generic algorithm is prefixed with the following definitions:

\SetKwProg{Fn}{Function}{}{end}\SetKwFunction{FRecurs}{FnRecursive}%
\newcommand{\forcond}{$i=0$ \KwTo $n$}

\documentclass{article}

\usepackage{algorithm2e}
\newcommand{\forcond}{$i=0$ \KwTo $n$}
\SetKwProg{Fn}{Function}{}{end}\SetKwFunction{FRecurs}{FnRecursive}%
\SetAlgoLongEnd

\begin{document}

\begin{algorithm}
  \Fn(\tcc*[h]{algorithm as a recursive function}){\FRecurs{some args}}{
    \KwData{Some input data\\these inputs can be displayed on several lines and one 
      input can be wider than line's width.}
    \KwResult{Same for output data}
    \tcc{this is a comment to tell you that we will now really start code}
    \If(\tcc*[h]{a simple if but with a comment on the same line}){this is true}{
      we do that, else nothing\;
      \tcc{we will include other if so you can see this is possible}
      \eIf{we agree that}{
        we do that\;
      }{
        else we will do a more complicated if using else if\;
        \uIf{this first condition is true}{
          we do that\;
        }
        \uElseIf{this other condition is true}{
          this is done\tcc*[r]{else if}
        }
        \Else{
          in other case, we do this\tcc*[r]{else}
        }
      }
    }
    \tcc{now loops}
    \For{\forcond}{
      a for loop\;
    }
    \While{$i<n$}{
      a while loop including a repeat--until loop\;
      \Repeat{this end condition}{
        do this things\;
      }
    }
    They are many other possibilities and customization possible that you have to
    discover by reading the documentation.
  }
\end{algorithm}

\end{document}

For other parts of the documentation, it redefined \Fn to display something else (depending on the output requirements).