Straight Line Equation Grapher

local width,height = 15,40

local gradient = height/width
local heightIntercept = -(gradient*width) + height

for w=1,width do
    local output = ""

  for h=1,height do
    equation = gradient*w + heightIntercept

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

    if w == 1 or h == 1 or w == width or h == height then
        output = output .. " "

    elseif h == equation then
        output = output .. "x"

    else
        output = output .. " "
    end
  end

  print(output)
end