From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


>>>
 It estimates the second
derivative of the error curve, as opposed to the first derivative in most
other tests - for this reason, it could perhaps be combined with a more
conventional test,
<<<

I was an enthusiastic supporter of the poor man's caustic test for many
years.  I have used it to great success in my own mirrors.  After the
mathematical discussion and my realization that the second derivative of
the curve can be just as misleading as the derivative of the curve, I
looked into how I could have used the test so well.  I concluded that I
never bothered testing until the Ronchi test showed I was close.  This
sidestepped the weaknesses of the poor man's caustic test.

Mel Bartels

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