Using standardized SI prefixes

Ben Finney bignose+hates-spam at
Wed Jun 13 23:49:08 UTC 2007

Ivan Jager <aij+nospam at> writes:

> On Wed, 13 Jun 2007, Alex Jones wrote:
> > 1 TB is not rounded. It means precisely 1 × 10^12 bytes, no more
> > and no less. If they want to actually put 1.024 TB on the disk
> > then they can say 1 TB (approx.) like any other industry
> > (detergent, bacon, etc.).
> 1 TB has only one significant digit. It would be silly to think that
> it was an exact measurement, at least in fields I am familiar
> with. ;) No one I know would think 1km is as precisely measured as
> 1.00000000000000000km.

The difference being that digital specifications for things like
storage capacity and memory are not measured. They are calculated, and
in those contexts they *are* precise.

Rounding can be done after the calculated number is obtained, but it's
not inherent in the process of obtaining the number the way that
measuring "1 km" or "1 tablespoon" is.

Since we *can* give a perfectly precise quantity of bytes and other
digital phenomena, and often do, this is even more reason to use the
precise meaning of the units for those quantities.

 \          "I moved into an all-electric house. I forgot and left the |
  `\   porch light on all day. When I got home the front door wouldn't |
_o__)                                         open."  -- Steven Wright |
Ben Finney

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