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Re: Calculator v. Slide Rule for Ex-Meridian Correction
From: Hewitt Schlereth
Date: 2015 Dec 31, 19:34 -0800
Greg, yes, here's to auld lang syne, logarithms, and slide rules.

Hewitt

On Dec 31, 2015, at 12:19 PM, Greg Rudzinski <NoReply_Rudzinski@fer3.com> wrote:

Image of competing calculating tools.

From: Greg Rudzinski
Date: 2015 Dec 31, 11:15 -0800

For a little fun on the final day of 2015 I did a time trial of the pocket trig calculator against the pocket 6" slide rule using the ex-meridian correction formula.

a = 1.964 (Cos Lat.) (Cos Dec.) / Sin (Lat. +/- Dec.)   } contrary name +    same name -

a(.267)(LHA t)(LHA t) = ex-meridian correction in minutes of arc added to Ho. The sum is solved as an LAN observation.

a= 1.964(Cos 34°10')(Cos 23°4')/Sin 57°14' = 1.778 by calculator   1.78 by slide rule

1.778(.267)(3.9°)(3.9°)= 7.22' by calculator   7.2' by slide rule

The calculator took 58 seconds with 57 button pushes.

The slide rule took 84 seconds with 6 moves of the slide and 6 moves of the cursor.

The calculator wins by only 24 seconds. Practical accuracy is even.

Greg Rudzinski

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