emove', function(e){
        var canvas_rect = polynomial.getBoundingClientRect();
           polynomial_draw(e.clientX - canvas_rect.left, e.clientY - canvas_rect.top, true);
           if(e.buttons == 1){
            polynomial_xs[polynomial_i] = client_to_x(e.clientX - canvas_rect.left);
            polynomial_ys[polynomial_i] = client_to_y(e.clientY - canvas_rect.top);
            polynomial_draw(e.clientX - canvas_rect.left, e.clientY - canvas_rect.top, false); // double work
           }
    }, false)