Hej Jason,

here is what you did:
start of animation: clock=0
end   of animation: clock=1

> sphere {0,1 pigment {rgb 1} scale 2*(clock+.0001) }
clock=0    scale 0.0002
clock=1    scale 2.0002

> sphere {0,1 pigment {rgb 1} scale -2*(clock+.0001) }
clock=0    scale -0.0002
clock=1    scale -2.0002
(same as above but mirrored)

> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/2 }
clock=0    scale 0.00005
clock=1    scale 0.50005

> sphere {0,1 pigment {rgb 1} scale (clock+.0001)/.5 }
exactly the same as number 1, because 1/.5=2

Here is what you could do:

linear
sphere {0,1 pigment {rgb 1} scale 1-clock }
clock=0    scale 1
clock=1    scale 0

slow in the beginning
sphere {0,1 pigment {rgb 1} scale 1-clock*clock }
clock=0    scale 1
clock=1    scale 0

fast in the beginning
sphere {0,1 pigment {rgb 1} scale (1-clock)*(1-clock) }
clock=0    scale 1
clock=1    scale 0

slow in the beginning
sphere {0,1 pigment {rgb 1} scale cos(pi*clock) }
clock=0    scale 1
clock=1    scale 0

fast in the middle
sphere {0,1 pigment {rgb 1} scale 0.5+0.5*cos(2*pi*clock) }
clock=0    scale 1
clock=1    scale 0

.....

You can even further modify these examples by including the expression
after "clock" in the equation "pow(<expression>,p)" with different
values for p.
1<p   => slower in the beginning, further acceleration to the end
0<p<1 => acceleration in the beginning, slowing down to the end

Or you could simply modify the range of the clock variable with the
commandline parameters "+KI" and "+KF"...


Uwe.

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