[Haskell-cafe] Re: Computer time, independent of date

ChrisK haskell at list.mightyreason.com
Sat Jan 10 18:00:13 EST 2009

Mauricio wrote:
> patients, I wanted to be sure not to save wrong
> information. It wouldn't matter if the clock is
> saying we are on XVII century, as long as 10 seconds
> would never be 10.1.

Chris (yes I am an experimental physicist) asks:

What are the interval durations you need to measure?
   0.1 second is very different from 1 ms or 0.1 μs !
   (1 ms is the atomic time radio signal accuracy)
   (0.1 μs can be had with GPS receivers)
   Since they are from equipment, what is the spec?
What is the error tolerance for these durations?
How are these errors allowed or forbidden to accumulate?

Since you say you do not trust the incoming timing then you need to be able to 
measure it.  Do you need to monitor the timing of each and every measurement 
while running?  Could you measure and certify the timing of the equipment before 
using it?  Got a cheap oscilloscope?

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