[Python-Dev] PEP 418: Add monotonic time, performance counter and process time functions
R. David Murray
rdmurray at bitdance.com
Wed Apr 18 21:58:20 CEST 2012
On Wed, 18 Apr 2012 15:50:13 -0400, Terry Reedy <tjreedy at udel.edu> wrote:
> On 4/18/2012 2:45 AM, Stephen J. Turnbull wrote:
> > On Wed, Apr 18, 2012 at 8:25 AM, Victor Stinner
> > <victor.stinner at gmail.com> wrote:
> >
> >> Ok ok, resolution / accuracy / precision are confusing (or at least
> >> not well known concepts).
> >
> > Maybe not to us, but in fields like astronomy and mechanical
> > engineering there are commonly accepted definitions:
> >
> > Resolution: the smallest difference between two physical values that
> > results in a different measurement by a given instrument.
> >
> > Precision: the amount of deviation among measurements of the same
> > physical value by a single instrument.
> >
> > Accuracy: the amount of deviation of measurements by a given
> > instrument from true values.
>
> These are standard definitions in US English that I learned in physics
> and statistics decades ago.
My problem was that I was confusing this definition of precision with
the "precision" of the computer representation of the number (that is,
the number of digits in the returned result).
--David
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