% Author: Dr. Henning Paul, DC4HP
% Year: 2022
\begin{tikzpicture}
	\pgfplotsset{
		every axis plot/.append style={line width=0.8pt},
	}
    \begin{axis}[%
        /pgf/number format/1000 sep={ },
        /pgf/number format/use comma,        
        axis lines=middle,
        axis line style={-Triangle},
		every axis x label/.style={at={(ticklabel* cs:1.02)},anchor=west,},
		every axis y label/.style={at={(ticklabel* cs:1.02)},anchor=south,},
        ytick style={draw=none},
		ymajorgrids=false,
        xticklabels={~~~~$\mathrm{T}$,~~~~~$2\mathrm{T}$,~~~~~$3\mathrm{T}$,~~~~~$4\mathrm{T}$},
		yticklabel=\empty,
		xtick={1,2,3,4},
        xmin=-0.5,
        xmax=3.7,
        ymin=-1.4,
        ymax=1.7,
        xmajorgrids=false,
        xlabel style={at={(ticklabel* cs:1)},anchor=north east},
        ylabel style={at={(ticklabel* cs:1)},anchor=south east},
        ylabel={$U$},
        xlabel={$t$},
        width=\linewidth*\getDarcImageFactor,
        height=2.5cm,
        scale only axis,
    ]
    \addplot[samples=101,domain=-1.0:0,black,dashed] {4.0*abs(mod(mod(x-0.25,1)+1.0,1.0)-0.5)-1.0}; 
   	\addplot[samples=301,domain=0.0:3.0,black] {4.0*abs(mod(mod(x-0.25,1)+1.0,1.0)-0.5)-1.0};
   	\addplot[samples=51,domain=3.0:3.5,black,dashed] {4.0*abs(mod(x-0.25,1)-0.5)-1.0}; 
\end{axis}
\end{tikzpicture}