#Another exercise page 4 et 5

Set $2Pi 6.28318530717959
Set $Factor Over 400 $2Pi

  Path {
    Width 1
    Move 100 400
    For $x0 0 200 {
      Set $x Times $x0 Over $2Pi 200
      Set $y Sin $x
      Set $t Plus 100 Times $x $Factor
      Set $u Plus 400 Times $y $Factor
      Line $t $u
    }
    Line 500 400
  }
  
Path {
    Width 0	# this means: as thin as possible
    Move 100 400
    Line 500 400
    Move 100 Minus 400 $Factor
    Line 100 Plus 400 $Factor
    # every pi/4 units:
    For $n 0 9 {
      Set $x Times $n Over $2Pi 8
      Set $t Plus 100 Times $x $Factor
      Move $t 390
      Line $t 410
    }
  }
