[ntp:questions] Re: announce: NTP FAQ v3.8
David J Taylor
david-taylor at invalid.com
Fri Jan 21 11:59:19 UTC 2005
Brad Knowles wrote:
> At 10:46 AM +0000 2005-01-21, David J Taylor wrote:
>> Mixing numbers like that is very confusing. My personal feelings
>> are that if you use PPM, then the units should be whole numbers: 15
>> PPM, 2 PPM etc, certainly /not/ fractional parts. If you must use
>> fractions, then not more than one decimal place - 1.6 PPM, 0.3 PPM If
>> you need to express smaller quantities, just stick with
>> scientific notation 1E-12, 1E-14 etc. Clarity of communication is
>> very important.
> The problem is that PPM is a standard measure. If you need to
> express smaller amounts, who is going to understand PPB, PPT (and
> would it mean Parts Per Thousand, or Parts Per Trillion?), PPP,
> Clarity of communication is important, but so is standardization of
>> Even better, of course, where you can use superscripts to write
>> 10-12, 10-14 (but not in this plain text e-mail!).
> Use caret. So, this becomes 10^-12 or 10^-14. Easy.
PPM is a standard measure, yes, but not the others. For accurate work
beyond that I think you need to use scientific notation. Do you think
10^-12 or 10E-12 is more widely understood?
By the way: in the VMS operating system one time unit was expressed in
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