187 lines
7.7 KiB
Plaintext
187 lines
7.7 KiB
Plaintext
From: SKYLRK::GIL "Gil Chinn (521-6402) J(ai)L Bird" 23-AUG-1986 11:01
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To: JAIL_BIRDS
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Subj: The "Ultimate" in SPR's (we're talking award winning)
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<<< EUREKA::DJA0:[NOTES$LIBRARY]JOKES.NOTE;1 >>>
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-< Laugh and the whole world laughs with you... >-
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================================================================================
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Note 151.3 SPRs 3 of 3
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TLE::HARRIS "Kevin Harris" 174 lines 19-AUG-1986 19:14
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-< The all time winner >-
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--------------------------------------------------------------------------------
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MAIL-11-To: "ELUDOM~WINALSKI"
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From: STAN AT TURTLE AT MRGATE
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Author: "Stanley Rabinowitz"
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Posted-date: 14-OCT-1983 @ 03:08:00
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Subject: My SPR answer (for your review)
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******DEC INTERNAL USE ONLY******
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SPR NUMBER: 11-60903
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ANSWER CATEGORY: UE
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MAINTENANCE HOURS: 1
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DUPLICATE PROBLEM: N
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DUPLICATE SPR NUMBER(S):
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OPERATING SYSTEM: VAX/VMS
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O.S. VERSION: V3.2
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PRODUCT: VAX/VMS
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PRODUCT VERSION: V3.2
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COMPONENT: Run-Time Library
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SUB-COMPONENT: LIB$ routines
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DATE ANSWERED: 13-Oct-1983
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MAINTAINER: Stanley Rabinowitz
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ATTACHMENT: N
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PUBLICATION INSTRUCTIONS: N
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SPR PROBLEM ABSTRACT: User claims year 2000 should not be a leap year.
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TITLE: -
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PUBLICATIONS: -
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ADDITIONAL O.S. VERSIONS:
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ADDITIONAL PRODUCT VERSIONS:
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COMPONENT SEQUENCE NUMBER:
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SUPERSEDES:
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TYPE OF ARTICLE:
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ANSWER CATEGORIES
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CG=1=CORRECTION GIVEN RS=5=RESTRICTION SG=9=SUGGESTION
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FN=2=FIXED IN NEXT RELEASE CS=6=CUSTOMER SUPPORTED IQ=10=INQUIRY
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DE=3=DOCUMENTATION ERROR NR=7=NON-REPRODUCIBLE HW=11=HARDWARE
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UE=4=USER ERROR II=8=INSUFFICIENT INFORMATION
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TYPE OF ARTICLE
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F=OPTIONAL FEATURE PATCH N=NOTE
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M=MANDATORY PATCH R=RESTRICTION
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FOR MAINTENANCE USE
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******END OF DEC USE ONLY******
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D I G I T A L
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SPR ANSWER FORM
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SPR NO. 11-60903
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SYSTEM VERSION PRODUCT VERSION COMPONENT
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SOFTWARE: VAX/VMS V3.2 VAX/VMS V3.2 Run-Time Library
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PROBLEM:
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The LIB$DAY Run-Time Library service "incorrectly" assumes the year
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2000 is a leap year.
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RESPONSE:
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Thank you for your forward-looking SPR.
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Various system services, such as SYS$ASCTIM assume that the year 2000
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will be a leap year. Although one can never be sure of what will
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happen at some future time, there is strong historical precedent for
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presuming that the present Gregorian calendar will still be in affect
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by the year 2000. Since we also hope that VMS will still be around by
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then, we have chosen to adhere to these precedents.
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The purpose of a calendar is to reckon time in advance, to show how
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many days have to elapse until a certain event takes place in the
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future, such as the harvest or the release of VMS V4. The earliest
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calendars, naturally, were crude and tended to be based upon the
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seasons or the lunar cycle.
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The calendar of the Assyrians, for example, was based upon the phases
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of the moon. They knew that a lunation (the time from one full moon
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to the next) was 29 1/2 days long, so their lunar year had a duration
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of 364 days. This fell short of the solar year by about 11 days.
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(The exact time for the solar year is approximately 365 days, 5 hours,
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48 minutes, and 46 seconds.) After 3 years, such a lunar calendar
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would be off by a whole month, so the Assyrians added an extra month
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from time to time to keep their calendar in synchronization with the
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seasons.
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The best approximation that was possible in antiquity was a 19-year
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period, with 7 of these 19 years having 13 months (leap months). This
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scheme was adopted as the basis for the religious calendar used by the
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Jews. (The Arabs also used this calendar until Mohammed forbade
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shifting from 12 months to 13 months.)
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When Rome emerged as a world power, the difficulties of making a
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calendar were well known, but the Romans complicated their lives
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because of their superstition that even numbers were unlucky. Hence
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their months were 29 or 31 days long, with the exception of February,
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which had 28 days. Every second year, the Roman calendar included an
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extra month called Mercedonius of 22 or 23 days to keep up with the
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solar year.
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Even this algorithm was very poor, so that in 45 BC, Caesar, advised
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by the astronomer Sosigenes, ordered a sweeping reform. By imperial
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decree, one year was made 445 days long to bring the calendar back in
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step with the seasons. The new calendar, similar to the one we now
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use was called the Julian calendar (named after Julius Caesar). It's
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months were 30 or 31 days in length and every fourth year was made a
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leap year (having 366 days). Caesar also decreed that the year would
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start with the first of January, not the vernal equinox in late March.
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Caesar's year was 11 1/2 minutes short of the calculations recommended
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by Sosigenes and eventually the date of the vernal equinox began to
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drift. Roger Bacon became alarmed and sent a note to Pope Clement IV,
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who apparently was not impressed. Pope Sixtus IV later became
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convinced that another reform was needed and called the German
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astronomer, Regiomontanus, to Rome to advise him. Unfortunately,
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Regiomontanus died of the plague shortly thereafter and the plans died
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as well.
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In 1545, the Council of Trent authorized Pope Gregory XIII to reform
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the calendar once more. Most of the mathematical work was done by
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Father Christopher Clavius, S.J. The immediate correction that was
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adopted was that Thursday, October 4, 1582 was to be the last day of
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the Julian calendar. The next day was Friday, with the date of
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October 15. For long range accuracy, a formula suggested by the
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Vatican librarian Aloysius Giglio was adopted. It said that every
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fourth year is a leap year except for century years that are not
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divisible by 400. Thus 1700, 1800 and 1900 would not be leap years,
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but 2000 would be a leap year since 2000 is divisible by 400. This
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rule eliminates 3 leap years every 4 centuries, making the calendar
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sufficiently correct for most ordinary purposes. This calendar is
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known as the Gregorian calendar and is the one that we now use today.
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(It is interesting to note that in 1582, all the Protestant princes
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ignored the papal decree and so many countries continued to use the
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Julian calendar until either 1698 or 1752. In Russia, it needed the
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revolution to introduce the Gregorian calendar in 1918.)
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This explains why VMS chooses to treat the year 2000 as a leap year.
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Despite the great accuracy of the Gregorian calendar, it still falls
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behind very slightly every few years. If you are very concerned about
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this problem, we suggest that you tune in short wave radio station
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WWV, which broadcasts official time signals for use in the United
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States. About once every 3 years, they declare a leap second at which
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time you should be careful to adjust your system clock. If you have
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trouble picking up their signals, we suggest you purchase an atomic
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clock (not manufactured by Digital and not a VAX option at this time).
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END OF SPR RESPONSE
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