[Tex/LaTex] How to add a big arrow

tikz-arrowstikz-pgf

I currently have this (done with LaTeX):

enter image description here

and I want to get this (done with OpenOffice):

enter image description here

How can I get those big arrows?

The complete document is here, the part in the pictures is:

\documentclass[a4paper,9pt]{scrartcl}
\usepackage{amssymb, amsmath} % needed for math
\usepackage[utf8]{inputenc} % this is needed for umlauts
\usepackage[ngerman]{babel} % this is needed for umlauts
\usepackage[T1]{fontenc}    % this is needed for correct output of umlauts in pdf
\usepackage[margin=2.5cm]{geometry} %layout

\begin{document}
\begin{tabular}{lll}
\textbf{Schritt 1}: euklidischer Algorithmus & & \textbf{Schritt 2}: nach Rest auflösen\\
$91=1 \cdot 71 + 21$    & $\rightarrow$     & $21 = 92 - 71$\\
$71=3 \cdot 21 + 8$     & $\rightarrow$     & $8 = 71 - 3 \cdot 21$\\
$21=2 \cdot 8 + 5$      & $\rightarrow$     & $5 = 21 - 2 \cdot 8$\\
$ 8=1 \cdot 5 + 3$      & $\rightarrow$     & $3 =  8 - 1 \cdot 5$\\
$ 5=1 \cdot 3 + 2$      & $\rightarrow$     & $2 =  5 - 1 \cdot 3$\\
$ 3=1 \cdot 2 + 1$      & $\rightarrow$     & $1 =  3 - 1 \cdot 2$
\end{tabular}

\textbf{Schritt 3}: so lange Reste einsetzen, bis eine Linearkombination der Form
$1 = x \cdot 92 + y \cdot 71$ gefunden ist:
\end{document}

(If there is a better way to do this than using tabular, e.g. align*, I could change it. However, I don't know how to get those big arrows anyway.)

Best Answer

How's this for a start?

enter image description here

My strategy:

  • Put a TikZ arrow in both columns of the first table row.

  • smash the arrows so they don't affect the layout of the table.

  • Place the point (-2,0) inside the boundingbox -- this hack serves to push each arrow 2cm to the right.

  • Adjust the baseline of the tikzpicture, which shifts the arrows up or down a little bit.

Code:

\documentclass[a4paper,9pt]{scrartcl}
\usepackage{amssymb, amsmath} % needed for math
\usepackage[utf8]{inputenc} % this is needed for umlauts
\usepackage[ngerman]{babel} % this is needed for umlauts
\usepackage[T1]{fontenc}    % this is needed for correct output of umlauts in pdf
\usepackage[margin=2.5cm]{geometry} %layout
\usepackage{tikz}
\usetikzlibrary{shapes.arrows}

\begin{document}

\def\myDownArrow{\smash{
  \begin{tikzpicture}[baseline=-2mm]
    \useasboundingbox (-2,0);
    \node[single arrow,draw=black,fill=black!10,minimum height=2cm,shape border rotate=270] at (0,-1) {};
  \end{tikzpicture}
}}
\def\myUpArrow{\smash{
  \begin{tikzpicture}[baseline=-1mm]
    \useasboundingbox (-2,0);
    \node[single arrow,draw=black,fill=black!10,minimum height=2cm,shape border rotate=90] at (0,-1) {};
  \end{tikzpicture}
}}

\begin{tabular}{lll}
\textbf{Schritt 1}: euklidischer Algorithmus & & \textbf{Schritt 2}: nach Rest auflösen\\
$91=1 \cdot 71 + 21$ \myDownArrow & $\rightarrow$     & $21 = 92 - 71$  \myUpArrow\\
$71=3 \cdot 21 + 8$     & $\rightarrow$     & $8 = 71 - 3 \cdot 21$\\
$21=2 \cdot 8 + 5$      & $\rightarrow$     & $5 = 21 - 2 \cdot 8$\\
$ 8=1 \cdot 5 + 3$      & $\rightarrow$     & $3 =  8 - 1 \cdot 5$\\
$ 5=1 \cdot 3 + 2$      & $\rightarrow$     & $2 =  5 - 1 \cdot 3$\\
$ 3=1 \cdot 2 + 1$      & $\rightarrow$     & $1 =  3 - 1 \cdot 2$
\end{tabular}

\textbf{Schritt 3}: so lange Reste einsetzen, bis eine Linearkombination der Form
$1 = x \cdot 92 + y \cdot 71$ gefunden ist:
\end{document}
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