# [Python-Dev] Subsecond time stamps

**Tim Peters
**
tim.one@comcast.net

*Fri, 06 Sep 2002 12:01:43 -0400*

[Paul Svensson]
>* Are C doubles dense enough to offer 100 ns resolution ?
*
The question can't be answered unless you also specify how many years you
want to cover. It takes about 25 bits to distinguish a year's worth of
seconds, and an IEEE double has 53 bits to play with. So if you were only
interested in representing one year, you've got about 28 bits left to play
with. If you want to cover an N-year span, you've got about 28 - log2(N)
bits to play with. It takes a bit over 23 bits to distinguish the number of
100 ns slices in a second, so N has to be small enough that 5 - log2(N)
doesn't go negative. So if you count the start of the epoch at 1970, you've
just created a year 2003 problem <wink>.