Arrows

\setlength{\unitlength}{1mm}
\begin{picture}(60, 40)
  \put(30, 20){\vector(1, 0){30}}
  \put(30, 20){\vector(4, 1){20}}
  \put(30, 20){\vector(3, 1){25}}
  \put(30, 20){\vector(2, 1){30}}
  \put(30, 20){\vector(1, 2){10}}
  \thicklines
  \put(30, 20){\vector(-4, 1){30}}
  \put(30, 20){\vector(-1, 4){5}}
  \thinlines
  \put(30, 20){\vector(-1, -1){5}}
  \put(30, 20){\vector(-1, -4){5}}
\end{picture}