%%BoundingBox: xmin ymin xmax ymax
%%BeginProlog
/Times-Roman findfont % get the basic font
24 scalefont % scale the font to 12 points
setfont % make it the current font

/arrowhead {% stack: s x1 y1, current point: x0 y0
gsave
currentpoint % s x1 y1 x0 y0
4 2 roll exch % s x0 y0 y1 x1
4 -1 roll exch % s y0 y1 x0 x1
sub 3 1 roll % s x1-x2 y0 y1
sub exch % s y0-y1 x1-x2
atan rotate % rotate over arctan((y0-y1)/(x1-x2))
dup scale % scale by factor s
-7 2 rlineto 1 -2 rlineto -1 -2 rlineto
closepath fill % fill arrowhead
grestore
newpath
} def

%%EndProlog

newpath
80 650 moveto 300 650 lineto stroke
newpath 300 650 moveto 3 -6000 800 arrowhead

newpath
100 630 moveto 100 820 lineto stroke
newpath 100 820 moveto 3 100 -4500 arrowhead