%!PS-Adobe-2.0
%%BoundingBox: 0 0 300 300

gsave

% draw graph of y = x^2 from 0 to 1

/S 150 def
S dup scale
1 S div setlinewidth

0.25 0.25 translate

gsave
newpath 
0 0 moveto
1 0 lineto
0 1 rlineto
0 1 lineto
closepath
0.7 setgray
stroke
grestore

% x -> x^2
/fcn {
dup mul 
} def

/N 10 def
/x 0 def
/dx 1 N div def
gsave
1 0 0 setrgbcolor
newpath
x dup fcn moveto
N {
  /x x dx add def
  x dup fcn lineto
} repeat
stroke
grestore

grestore

% add the label
% the label is produced by TEX and dvips 

gsave
100 78 translate
2 2 scale
49 rotate
(yx2.lbl) run
grestore

showpage