To: atm{at}shore.net
From: MLThiebaux 
Reply-To: MLThiebaux 


George Anderson wrote:
>While trying to improve the mediocre performance of my corrector design
>I started wondering about my interpretation of some of the formulas in
>R&V Telescope Optics.
>On page 301 and 302 I have been trying to decide if there are
>inconsistencies in the typsetting.
>Formula 21.11.2 uses a multiply point sign between hp and the sqrt sign
>with no root number in the sign (normal from what I remember from
>college). Yet 21.11.4 has a 2 beside the sqrt sign with no multiply
>point. Are they saying multiply the sqrt by 2 or are they just
>emphasizing that it is root 2?
>Same thing with 21.11.6 on pg 302, is it r times the sqrt or is it the r
>root of...?
>...
...
>George Anderson
>Montreal Canada
>
>Clear skies and good health
>

Here are some comments on mathematical notation:

No significance should be attached to the irregular appearance of the
multiply point or cross.  The practice is common but sloppy unless used for
emphasis as was probably the intention in R&V Telescope Optics.

The  2  as a root is NEVER displayed in the notch of the radical sign.
Besides, the  2  and  r  referred to are in the wrong positions to be
interpreted as roots.

Also  r  couldn't be a root because it is a dimensioned quantity (length).
Roots must be dimensionless numbers.

Finally, I'm almost 100% sure that the only roots you would ever see in
optical formulas would be square roots.

Martial Thiebaux
Rawdon Hills, Nova Scotia

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