\begin{pspicture}(-1,-1)(4.9,4.9)
 %\psgrid[griddots=10,gridlabels=0pt, subgriddiv=0]
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Koordinaten%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \psaxes[Ox=0,Dx=2,Oy=0,Dy=2,linewidth=0.1pt]{->}(0,0)(-0.0,-0.0)(4.5,4.5)%Schnittpunkt, x0, y0   x1,y1
 \rput[c](4.8,0){$x$} 
 \rput[c](0,4.8){$y$}
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Vektor%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \psline[linecolor=red, linewidth=0.1pt]{->}(0,0)(3,3)
  
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%Hilfslinien%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \psline[linecolor=blue, linestyle=dashed, linewidth=0.1pt](3,-0.2)(3,3)
 \psline[linecolor=blue, linestyle=dashed, linewidth=0.1pt](-0.2,3)(3,3)
 \rput[c](3.0,-0.3){$a_1$}
 \rput[c](-0.3,3){$a_2$}
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%Pfeil mit Beschriftung%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \psline{->}(3.5,2.5)(3.1,2.9)
 \rput[l](1.8,2.3){$Vektor\ ("`Pfeil"')$}
 \rput[l](2.5,1.9){$\vec{a}$}
 
 
 
 
  \end{pspicture}