[ATM] Starlaps (aka petal, deformed, Zulu laps)

[Jim Burrows <burrjaw@earthlink.net>]

Tex sez, p. 95, "...it is difficult to control fully the effect produced or 
to terminate the action abruptly once the defect is sufficiently 
minimized."  I hadn't thought of the spell-length problem still remaining 
even when the starlap has "fully controlled effect", i.e., scaled with most 
action at the deviation peak down to zero action at the valley.

For example, I simulated parabolizing an 8"f/6 sphere with a perfect 
starlap.  As the spell length increased, the conic constant b decreased 
steadily: 0 ... -.5 ... -1 ... oops, going hyperbolic, at which point the 
starlap is now perfectly wrong.

My starlap design program has a scaling parameter - guess I'll try reducing 
it for my 10"f/2.6 RC primary refiguring - the last 30 s spell really overshot.

         -- Jim Burrows
         -- mailto://burrjaw@earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84)  

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