How to create outward spiral motion in Adobe After Effects? I want to create an outward spiral motion in Adobe AE. So how to do it?

I found an expression script for it here but it creates an inward spiral motion and I want outward spiral. And I am not able to reverse it.

shrink=time+1
radius=1000/shrink
angle=time*200
x=radius*Math.cos(degreesToRadians(angle))
y=radius*Math.sin(degreesToRadians(angle))
//z=0 // no depth
z=time*time // with depth
centre=[640,360,0]
add(centre,[x,y,z])


What exactly I want to do?

I want the images to spiral in a circular image from center to some particular points in the circle. And then they stop spiralling and stay at that point.
And after a while they shift to left with the whole circular image.

Please help.
That script uses the variable shrink, which paradoxically increases with time. Just make it decrease with time, e.g. by replacing the first line with these two:

var endTime =  123; //how long you want it to take, in seconds
shrink = endTime - time;


Or make the radius the product of the time and a constant, rather than dividing the radius by time, by replacing the first two lines with these:

shrink= time;
radius = 100 * time; //this will grow 100 pixels every second, adjust to suit


Or parent the images to a null, rotate it and scale it up. Then to counter the rotation and scale of the null on each image use this expression for rotation

0 - parent.transform.rotation


and for scale:

100 / parent.scale