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epoch 音标拼音: ['ɛpək] ['ipək] n. 新纪元,时代,时期 新纪元,时代,时期 epoch n 1: a period marked by distinctive character or reckoned from a fixed point or event [ synonym: { era}, { epoch}] 2: ( astronomy) an arbitrarily fixed date that is the point in time relative to which information ( as coordinates of a celestial body) is recorded [ synonym: { epoch}, { date of reference}] 3: a unit of geological time that is a subdivision of a period and is itself divided into agesEpoch \ Ep" och\ ([ e^] p"[ o^] k or [= e]" p[ o^] k; 277), n. [ LL. epocha, Gr. ' epochh` check, stop, an epoch of a star, an historical epoch, fr. ' epe` chein to hold on, check; ' epi` upon ' e` chein to have, hold; akin to Skr. sah to overpower, Goth. sigis victory, AS. sigor, sige, G. sieg: cf. F. [' e] poque. See { Scheme}.] 1. A fixed point of time, established in history by the occurrence of some grand or remarkable event; a point of time marked by an event of great subsequent influence; as, the epoch of the creation; the birth of Christ was the epoch which gave rise to the Christian era. [ 1913 Webster] In divers ages, . . . divers epochs of time were used. -- Usher. [ 1913 Webster] Great epochs and crises in the kingdom of God. -- Trench. [ 1913 Webster] The acquittal of the bishops was not the only event which makes the 30th of June, 1688, a great epoch in history. -- Macaulay. [ 1913 Webster] Note: Epochs mark the beginning of new historical periods, and dates are often numbered from them. [ 1913 Webster] 2. A period of time, longer or shorter, remarkable for events of great subsequent influence; a memorable period; as, the epoch of maritime discovery, or of the Reformation. " So vast an epoch of time." -- F. Harrison. [ 1913 Webster] The influence of Chaucer continued to live even during the dreary interval which separates from one another two important epochs of our literary history. -- A. W. Ward. [ 1913 Webster] 3. ( Geol.) A division of time characterized by the prevalence of similar conditions of the earth; commonly a minor division or part of a period. [ 1913 Webster] The long geological epoch which stored up the vast coal measures. -- J. C. Shairp. [ 1913 Webster] 4. ( Astron.) ( a) The date at which a planet or comet has a longitude or position. ( b) An arbitrary fixed date, for which the elements used in computing the place of a planet, or other heavenly body, at any other date, are given; as, the epoch of Mars; lunar elements for the epoch March 1st, 1860. Syn: Era; time; date; period; age. Usage: { Epoch}, { Era}. We speak of the era of the Reformation, when we think of it as a period, during which a new order of things prevailed; so also, the era of good feeling, etc. Had we been thinking of the time as marked by certain great events, or as a period in which great results were effected, we should have called the times when these events happened epochs, and the whole period an epoch. [ 1913 Webster] The capture of Constantinople is an epoch in the history of Mahometanism; but the flight of Mahomet is its era. -- C. J. Smith. [ 1913 Webster] 20 Moby Thesaurus words for " epoch": Bronze Age, Dark Ages, Depression Era, Golden Age, Ice Age, Iron Age, Jacksonian Age, Middle Ages, New Deal Era, Prohibition Era, Silver Age, Steel Age, Stone Age, age, days, era, glacial epoch, interval, term, time1. (Probably from astronomical timekeeping)
A term used originally in {Unix} documentation for the time
and date corresponding to zero in an {operating system}'s
{clock} and {timestamp} values.
Under most Unix versions the epoch is 1970-01-01 00:00:00 GMT;
under {VMS}, it's 1858-11-17 00:00:00 (the base date of the US
Naval Observatory's ephemerides); on a {Macintosh}, it's
1904-01-01 00:00:00.
System time is measured in seconds or {ticks} past the epoch.
Weird problems may ensue when the clock wraps around (see
{wrap around}), which is not necessarily a rare event; on
systems counting 10 ticks per second, a signed 32-bit count of
ticks is good only for 0.1 * 2**31-1 seconds, or 6.8 years.
The one-tick-per-second clock of Unix is good only until
2038-01-18, assuming at least some software continues to
consider it signed and that word lengths don't increase by
then. See also {wall time}.
2. (Epoch) A version of {GNU Emacs} for the {X Window
System} from {NCSA}.
[{Jargon File}]
(2004-06-10)
epoch: n. [ Unix: prob.: from astronomical timekeeping] The time and date corresponding to 0 in an operating system' s clock and timestamp values. Under most Unix versions the epoch is 00: 00: 00 GMT, January 1, 1970; under VMS, it' s 00: 00: 00 of November 17, 1858 ( base date of the U. S. Naval Observatory' s ephemerides); on a Macintosh, it' s the midnight beginning January 1 1904. System time is measured in seconds or ticks past the epoch. Weird problems may ensue when the clock wraps around ( see wrap around), which is not necessarily a rare event; on systems counting 10 ticks per second, a signed 32- bit count of ticks is good only for 6. 8 years. The 1- tick- per- second clock of Unix is good only until January 18, 2038, assuming at least some software continues to consider it signed and that word lengths don' t increase by then. See also wall time. Microsoft Windows, on the other hand, has an epoch problem every 49. 7 days — but this is seldom noticed as Windows is almost incapable of staying up continuously for that long.
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