int a to v const a

• Constant acceleration $$\tag{A1} a(t) = a_n, \ \ \ \ t_n < t < t_{n+1}. $$
• Initial condition $$\tag{A2} v(t_n) = v_n. $$
• Velocity $$\tag{A3} v(t) = v_n + a_n(t - t_n), \ \ \ \ t_n \le t \le t_{n+1}. $$