documentclass[paper=a4,12pt,version=last]{scrartcl}
usepackage[miktex]{gnuplottex}
usepackage{pgfplots}
usepackage{pgfplotstable}
pgfplotsset{compat=newest}

begin{document}
section{PGFPLOTS}
Note how the tick labels match the document font.

begin{tikzpicture}
begin{axis}[domain=-10:10, samples=50, smooth, no markers, enlargelimits=false]
addplot gnuplot {sin(x)}; addlegendentry{$sin(x)$}
addplot gnuplot {cos(x)}; addlegendentry{$cos(x)$}
end{axis}
end{tikzpicture}
end{document}

pdflatex -synctex=1 -interaction=nonstopmode %.tex

pdflatex -shell-escape -synctex=1 -interaction=nonstopmode %.tex

addplot gnuplot ...

documentclass[paper=a4,fontsize=12pt,version=last]{scrartcl}
usepackage{pgfplots}
pgfplotsset{compat= newest, width=10cm, }
begin{document}
begin{figure}
centering
begin{tikzpicture}
begin{axis}[
height=9cm,
width=9cm,
grid=minor,
]
addplot gnuplot[id=filesuffix]{(-x**5 - 242)};
addlegendentry{model}
end{axis}
end{tikzpicture}
end{figure}
end{document}

documentclass [12pt, a4paper, headinclude, titlepage]{scrartcl}
usepackage[ngerman]{babel}
usepackage[fixlanguage]{babelbib}
selectbiblanguage{german}
usepackage[utf8]{inputenc}
usepackage[T1]{fontenc}
usepackage[a4paper]{geometry}
usepackage[fleqn]{amsmath}
usepackage{pgfplots}
usepackage{pgf}
usepackage{tikz}
usepackage{float}

pgfplotsset{width=7cm, compat=newest}

begin{document}
begin{figure}[H]
centering
begin{tikzpicture}
 begin{axis}
     [  ylabel=$kappa$ / (S/m) , xlabel=c / (mol/m$^3$), title=textbf{c gegen $kappa$},
        xmin=0, xmax=130,
        ymin=0,  ymax=0.3,
        width=0.6textwidth, height=0.45textwidth, x axis line style={-}, y axis line                     style={-},
      ]
         addplot [only marks, gray, raw gnuplot, id=raw3] function{plot 'Daten.txt' u 1:2};
             addplot [orange, dashed, raw gnuplot, id=raw3] function{plot 'ber.txt' u 1:3};
     end{axis}
end{tikzpicture}
caption{Auftragung der Messwerte c gegen $kappa$ (grau) und der berechneten Werte (orange)}
end{figure}
end{document}