NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Henning Umland's programs?
From: Hanno Ix
Date: 2013 May 10, 14:47 -0700
From: Greg Rudzinski <gregrudzinski@yahoo.com>
To: hannoix@att.net
Sent: Thursday, May 9, 2013 8:01 PM
Subject: [NavList] Re: Henning Umland's programs?
From: Hanno Ix
Date: 2013 May 10, 14:47 -0700
I followed this discussion with interest. I have thought about the issue at length and
came to the following conclusion:
Since the std unit of length AND the std unit of angle is the arc min = sea mile
anyway I have adopted to transfer all angles to multiples of
this unit.
The advantages are indeed numerous:
1. I do only integer arithmetic except for the xformation itself.
2. I never do sexagesimal arithmetic, or worse, bot:
12deg 15 min 43.7" minus 36deg 24' 48.80 ".
This is, in my eyes, insane, and even with a calculator, errors are still frequent
while at the same time the apparent resolution is technically meaningless.
3. Since 90 deg = 5400 ' it is sufficient to work with four, or max 5, digits.
I round seconds to the next integer.
BTW: For these very reasons the French invented the meter, better, the kilometer:
For CelNav, the angle from the equator to the pole is exactly 10,000 km.
The English didn't like anything Continental - they still don't - so they kept
making CelNav much more painful
and error-prone - with a stiff upper lip.
For reason of tradition and communication etc, I continue to use the traditional unit
modified as described above doing, however, my calculations entirely in the decimal
world and integer numbers.
If you think that is impossible I shall shortly proof to you otherwise. I will also proof
to you that it can be done with high
accuracy and ease.
h
From: Greg Rudzinski <gregrudzinski@yahoo.com>
To: hannoix@att.net
Sent: Thursday, May 9, 2013 8:01 PM
Subject: [NavList] Re: Henning Umland's programs?
Samuel,
11' 45" = 11.7' (divide seconds of arc by 60 and round to the nearest tenth)
It is much easier to do it this way. 1' = 1 nautical mile thus 0.1' = 1 tenth of a nautical mile. Working in seconds of arc isn't practical. When reading the sextant micrometer drum I hope you are getting minutes and tenths. The Nautical Almanac uses minutes and tenths also. Latitude, longitude, declination, GHA, LHA, all need to be in minutes and tenths otherwise you are looking for trouble.
Greg Rudzinski
Re: Henning Umland's programs?
From: Samuel
Date: 2013 May 9, 19:32 -0700
I still don't understand the minutes and seconds format.
From: Samuel
Date: 2013 May 9, 19:32 -0700
I still don't understand the minutes and seconds format.
Example 123 degrees 11' 45"
For Umland's program (Sight Reduction) would that be 123 (degrees) then in the next box 11.45 minutes?
If I'm wrong how would the example above be expressed?
Thank
you.
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