Short-circuit Logic

[Carlos Nepomuceno]

----------------------------------------
> To: python-list at python.org
> From: wlfraed at ix.netcom.com
> Subject: Re: Short-circuit Logic
> Date: Thu, 30 May 2013 19:38:31 -0400
>
> On Thu, 30 May 2013 08:48:59 -0400, Roy Smith <roy at panix.com> declaimed
> the following in gmane.comp.python.general:
>
>>
>> Analysis of error is a complicated topic (and is much older than digital
>> computers). These sorts of things come up in the real world, too. For
>> example, let's say I have two stakes driven into the ground 1000 feet
>> apart. One of them is near me and is my measurement datum.
>>
>> I want to drive a third stake which is 1001 feet away from the datum.
>> Do I measure 1 foot from the second stake, or do I take out my
>> super-long tape measure and measure 1001 feet from the datum?
>
> On the same azimuth? Using the "super long tape" and ensuring it
> traverses the 1000 foot stake is probably going to be most accurate --
> you only have the uncertainty of the positioning of the tape on the
> datum, and the small uncertainty of azimuth over the 1000 foot stake.
> And even the azimuth error isn't contributing to the distance error.
>
> Measuring 1 foot from the 1000 foot stake leaves you with any error
> from datum to the 1000 foot, plus any error from the 1000 foot, PLUS any
> azimuth error which would contribute to shortening the datum distance.

Just because you have more causes of error doesn't mean you have lesser accurate measures.

If fact, errors may compensate each other. It all depends on the bias (accuracy) and variation (precision) involved in the measurements you are considering.

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> Wulfraed Dennis Lee Bieber AF6VN
> wlfraed at ix.netcom.com HTTP://wlfraed.home.netcom.com/
>
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