On Tue, 23 Nov 2004, Martin Maechler wrote:
"james" == james holtman <[EMAIL PROTECTED]> on Tue, 23 Nov 2004 10:39:04 -0500 writes:
james> You might want to check out 'chron'. This stores the james> time as days and fractions of a day.
james> If you take the current date,
>> as.numeric(chron(dates.="11/23/2004")) james> [1] 12745 >>
james> you get the value above. If you change this to james> millisecond, you get
>> as.numeric(chron(dates.="11/23/2004")) * 86400 * 1000 james> [1] 1.101168e+12 >>
james> this value requires 46 bits and since a floating james> point number has 54 bits of value,
no, only 52 bits (64 = 52+1+12+1) with sign bits for exponent and mantissa.
But with an implicit '1' for the first digit in a normalized number.
http://docs.sun.com/source/806-3568/ncg_math.html is one source. E.g.
`The 52-bit fraction combined with the implicit leading significand bit provides 53 bits of precision in double-format normal numbers.'
-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
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