MODE 8
      *FLOAT 64
      VDU 23,23,4;0;0;0; : REM Set line thickness

      theta = RAD(40) : REM initial displacement
      g = 9.81 : REM acceleration due to gravity
      l = 0.50 : REM length of pendulum in metres

      REPEAT
        PROCpendulum(theta, l)
        WAIT 1
        PROCpendulum(theta, l)
        accel = - g * SIN(theta) / l / 100
        speed += accel / 100
        theta += speed
      UNTIL FALSE
      END

      DEF PROCpendulum(a, l)
      LOCAL pivotX, pivotY, bobX, bobY
      pivotX = 640
      pivotY = 800
      bobX = pivotX + l * 1000 * SIN(a)
      bobY = pivotY - l * 1000 * COS(a)
      GCOL 3,6
      LINE pivotX, pivotY, bobX, bobY
      GCOL 3,11
      CIRCLE FILL bobX + 24 * SIN(a), bobY - 24 * COS(a), 24
      ENDPROC