[time-nuts] Standards for units

[David Forbes]

At 9:57 PM -0700 4/2/07, Tom Van Baak wrote:
>>  >1/meter/39.37 inches = 0.025400051 meters/inch ...
>
>>  The interesting thing is that this result is off by  2.000004000 ppm.
>>  That's a rather precise error!
>>
>>  The calculator I used is here:
>>  http://homepage.ntlworld.com/r.howitt/Calculator.htm
>
>David,
>
>There are two ways to compute relative error, depending on
>which one you call the reference.
>
>For extra credit, note your number is actually this cool-looking
>fraction* whose pattern you will immediately recognize.
>
>2.000004000008000016000032000064000128000256000512001024...
>
>/tvb
>http://www.LeapSecond.com
>
>* calculated with: echo "80k .002 999.998 / 10 6 ^ * p" | dc


Yes, I had a feeling it was that case, but I didn't bother to chase it too far.

This precise sort of error reminds me of the error that RCA 
introduced into the frame rate for NTSC color when they discovered 
that the chosen color burst frequency was right on top of a diathermy 
machine or something silly like that. They bumped the frame rate down 
by exactly 0.1%, creating the 29.97 frames/second that 
cinematographers have grown to love to hate.

There's a volume of the RCA Review that came out in 1953 that is all 
about the NTSC color system development process. It's fascinating 
reading. Available at your local university library.


-- 

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/