I made a little illustration for this math gem collection:
http://math.stackexchange.com/a/508660/16936
Here is the code:
%!
%
ennead.ps
%
luser...@gmail.com
/pt {
-40 mul
dup cos exch sin
} def
/size {
false charpath flattenpath pathbbox % left bot right top
3 -1 roll sub % left right top-bot
3 1 roll exch sub % top-bot right-left
exch % right-left top-bot
pstack()=
} def
300 400 translate
currentlinewidth 30 dup dup scale div setlinewidth
90 rotate
9 pt moveto
3 pt lineto
6 pt lineto
closepath
stroke
1 pt moveto
4 pt lineto
2 pt lineto
8 pt lineto
5 pt lineto
7 pt lineto
closepath
stroke
/Courier .4 selectfont
1.5 dup scale
1 1 9 {
dup pt moveto
gsave
-90 rotate
( ) cvs
dup size
exch -2.5 mul
exch -.7 mul
rmoveto
show
grestore
} for
showpage
%eof