This html code uses "canvas" element, for which the positive x-axis is rightward (same as we usually draw on graphs),
whereas positive y-axis is downward. Hence, in this system the positive angle is measured from positive x-axis clockwise.
Similarly, positive angular velocity is clockwise and so does the positive angular acceleration.
Set the link lengths for the mechanism and see it moving.
Input the link lengths
Press the "Animate" button again to speed up the mechanism.