This example demonstrates accelerando by playing 7-note scale (diatonic) over five octaves while increasing the velocity from soft to loud (20 to 125), and also the rate from 2 to 22 notes per second.
Note the importance of the right-to-left ordering of Max messages here. The rate of the metro is initialized first (also setting the duration of the first note) before the metro is started. The velocity values are produced next, so that they will have already been received by makenote when the pitch values arrive. After each note is played, a new rate is given to the metro (and a new duration to makenote) in preparation for the subsequent note. The metro stops after the last note is played.