Added sigmoid-function

tikz/sigmoid-function/sigmoid-function.tex

@@ -0,0 +1,34 @@
+\documentclass[varwidth=false, border=2pt]{standalone}
+
+\usepackage{pgfplots}
+\usepackage{tikz}
+\usepackage{tkz-fct}
+\usetikzlibrary{arrows}
+
+\begin{document}
+\begin{tikzpicture}
+    \begin{axis}[
+    	legend pos=north west,
+        axis x line=middle,
+        axis y line=middle,
+        grid = major,
+        width=16cm,
+        height=8cm,
+        grid style={dashed, gray!30},
+        xmin=-1,     % start the diagram at this x-coordinate
+        xmax= 1,    % end   the diagram at this x-coordinate
+        ymin= 0,     % start the diagram at this y-coordinate
+        ymax= 1,   % end   the diagram at this y-coordinate
+        %axis background/.style={fill=white},
+        xlabel=x,
+        ylabel=y,
+        tick align=outside,
+        enlargelimits=false]
+      % plot the stirling-formulae
+      \addplot[domain=-1:1, red, ultra thick,samples=500] {1/(1+exp(-5*x))}; 
+      \addplot[domain=-1:1, blue, ultra thick,samples=500] {1/(1+exp(-10*x))}; 
+      \addlegendentry{$f(x)=\frac{1}{1+e^{-5x}}$}
+      \addlegendentry{$g(x)=\frac{1}{1+e^{-10x}}$}
+    \end{axis} 
+\end{tikzpicture}
+\end{document}