%!PS-Adobe-2.0
%%BoundingBox: 0 0 300 150

150 75 translate

/pi 3.1415926536 def
% referring to pi as //pi will embed it in line as a constant

% t [f p] -> cos(f t - p) 
/f { 1 dict begin
% change radians to degrees
  aload pop
  /p exch def
  /f exch def
  /t exch //pi div 180 mul def
  f t mul p sub cos 
end } def

/S 36 def
S dup scale
1 S div setlinewidth

/llx -6 def
/urx 6 def
/N 200 def

gsave
1 0 0 setrgbcolor
newpath
llx 0 moveto
urx 0 lineto
0 -2.25 moveto
0  2.25 lineto
stroke
grestore

/dx urx llx sub N div def
/x llx def

newpath
x dup [1 0] f moveto
N {
  /x x dx add def
  x dup [1 0] f lineto
} repeat
stroke