arrow.ps

/arrowdict 14 dict def
arrowdict begin
  /mtx matrix def
end

/arrow {              % This routine is borrowed from the
                      % "PostScript Language - Tutorial & Cookbook"
   arrowdict begin
      /hl exch def
      /ht exch 2 div def
      /t  exch 2 div def
      /hy exch def
      /hx exch def
      /ty exch def
      /tx exch def

      /dx hx tx sub def
      /dy hy ty sub def
      /al dx dx mul dy dy mul add sqrt def
      /angle dy dx atan def
      /base al hl sub def

      /savematrix mtx currentmatrix def

      tx ty translate
      angle rotate

      0 t neg moveto
      base t neg lineto
      base ht neg lineto
      al 0 lineto
      base ht lineto
      base t lineto
      0 t lineto
      closepath

      savematrix setmatrix
   end
} def