Sub DrawFormatedLine (x1,y1,x2,y2)
   ' slightly convert values to fit screen with zooming
   DrawLine(x1*50+100,y1*50+75,x2*50+100,y2*50+75)
End Sub

FromX = -10
ToX = 15
StepX = 0.05
Ax = FromX ' prev value
Ay = Sin(Ax) ' prev value

SetPenColor(Rgb(0,0,150))
DrawFormatedLine (-10,0,15,0) ' Draw X accis
DrawFormatedLine (0,-3,0,3) ' Draw y accis

SetPenColor(Rgb(200,0,0))
For x=FromX to ToX Step StepX
  y = Sin(x)
  DrawFormatedLine(Ax,Ay, x,y)
  Ax = x
  Ay = y
Next

SetPenColor Rgb(0,150,0)
DrawText "Press a key to exit",450,185
while not readkey wend