grid

grid = {}
width, height = term.getSize()
gradient = height/width
heightIntercept = -(gradient*width) + height

for w=1,width do
  grid[w] = {}

  for h=1,height do
    grid[w][h] = ""
    equation = gradient*w + heightIntercept

    if equation%1 < 0.5 then
      equation = math.floor(equation)
    else
      equation = math.ceil(equation)
    end

    term.setCursorPos(w,h)

    if w == 1 or h == 1 or w == width or h == height then
      term.setBackgroundColor(colors.green)
      term.write(" ")

    elseif h == equation then
      term.setBackgroundColor(colors.green)
      term.write("x")

    else
      term.setBackgroundColor(colors.lime)
      term.write(" ")
    end
  end
end

sleep(2)