[Here](https://drakeluce.com/betterthandesmos/?function=Math.sin(x)*Math.sin((Date.now()%2F1000))%0AMath.cos(x)*Math.cos((Date.now()%2F1000))%0AMath.tan(x)*Math.tan((Date.now()%2F1000))) is a good example of this happening. Because of the thresholding to prevent vertical bars, sometimes the secant line gets funky. There's probably a function that can determine when it's acceptable to not render a line. Function of slope?