computercraft sine wave animation

--Draws an animated sinewave
m = peripheral.wrap("right")
local theta = 0
local yvalues = {}

function draw()
   calc()
   render()
end

function calc()
   x,y = m.getSize()
   amplitude = math.floor(y/2) -2
   period = x/2
   dx = (math.pi*2) / period
   theta = theta + .02

   for i=0, x do
      yvalues[i] = math.sin(theta) * amplitude
      theta = theta + dx
   end

end

function render()
   m.setBackgroundColor(colors.black)
   m.clear()

   for i=1, #yvalues do
      m.setCursorPos(i, (y/2)+ math.floor(yvalues[i]) +1)
      m.blit(" ","0", "0")

   end

end

while true do
   draw()
   sleep(.1)
end