Thank you, wyz;
I solved my problem with your help.

Here is mine:

freq=0.05;
amplitude=1;
p=amplitude*Math.cos(freq*YRotation+6.3);
p*100

And, how to control the curvature or swings?

I want to turn the expression values into keyframes, just like Combustion could do.

Thanx for reply.

"Random" usually generates a value on every frame, but I only need the random value on every second or more. How could I use it?

Do v1.3 and v1.4. work only on over 20 mission-quque?

And, on 1.1 and 1.2 version, the scroll bar seems badly controlled.
Could 1.2 script has a perfect scroller or 1.4 runs under 20 mission-queue?

BTW, A_Muster_Submit_v1_1.jsx is well done work.

Thanx for your work.