Daylight saving correction

Discussion in 'Java' started by Roedy Green, Mar 14, 2010.

  1. Roedy Green

    Roedy Green Guest

    Your computer should have automatically set your PC clock ahead 1 hour
    at 2AM this morning. If you want to check that it worked ok, and if
    not correct the problem and resynch your clock with an atomic source,
    see

    http://mindprod.com/webstart/setclock.html

    for general lore on DST see
    http://mindprod.com/jgloss/dst.html

    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 14, 2010
    #1
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  2. Roedy Green

    Roedy Green Guest

    On Sun, 14 Mar 2010 09:22:18 -0700, Roedy Green
    <> wrote, quoted or indirectly quoted
    someone who said :

    >Your computer should have automatically set your PC clock ahead 1 hour
    >at 2AM this morning.


    That applies to the USA and Canada only. Other parts of the world
    will have other correction dates.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 14, 2010
    #2
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  3. Roedy Green

    Arne Vajhøj Guest

    On 14-03-2010 12:22, Roedy Green wrote:
    > Your computer should have automatically set your PC clock ahead 1 hour
    > at 2AM this morning. If you want to check that it worked ok, and if
    > not correct the problem and resynch your clock with an atomic source,
    > see


    C:\>javac DST.java
    DST.java:1: class, interface, or enum expected
    Your computer should have automatically set your PC clock ahead 1 hour
    ^
    1 error

    Arne
     
    Arne Vajhøj, Mar 14, 2010
    #3
  4. Roedy Green

    Arne Vajhøj Guest

    On 14-03-2010 12:23, Roedy Green wrote:
    > On Sun, 14 Mar 2010 09:22:18 -0700, Roedy Green
    > <> wrote, quoted or indirectly quoted
    > someone who said :
    >> Your computer should have automatically set your PC clock ahead 1 hour
    >> at 2AM this morning.

    >
    > That applies to the USA and Canada only.


    And only to OS's that has such a feature.

    But it is still not on topic here.

    Arne
     
    Arne Vajhøj, Mar 14, 2010
    #4
  5. In comp.lang.java.programmer message <i53qp5dnm4ro53afcfkqvbgqr7kl9g4dea
    @4ax.com>, Sun, 14 Mar 2010 09:22:18, Roedy Green <see_website@mindprod.
    com.invalid> posted:
    >Your computer should have automatically set your PC clock ahead 1 hour
    >at 2AM this morning.


    Codswallop and balderdash. The proper date for that is the last Sunday
    in March and the proper time is 01:00 UTC (or GMT), which all Canadians
    should realise. The proper date to change back is the last Sunday in
    October, at the same UTC.

    Except, of course, for those in the Southern Hemisphere.

    Both except those near the Equator, in Iceland, or on the ISS - etc.

    --
    (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
    Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
    PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
    Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
     
    Dr J R Stockton, Mar 16, 2010
    #5
  6. On 03/14/2010 12:22 PM, Roedy Green wrote:
    > Your computer should have automatically set your PC clock ahead 1 hour
    > at 2AM this morning. If you want to check that it worked ok, and if
    > not correct the problem and resynch your clock with an atomic source,
    > see
    >
    > http://mindprod.com/webstart/setclock.html


    Only if you are part of the ~5% of the world population who lives in
    parts of North America and the Caribbean islands.

    A more complete (but not fully correct) chart, taken courtesy of another
    newsgroup that requires coordination between people from many different
    countries (most notably U.S., Canada, a variety of European countries,
    New Zealand, Japan, among others):

    Sunday, February 21:
    -1 hour: South, Southeast, and Central-West Brazil (GO, DF, MG, ES, RJ,
    SP, PR, SC, RS, MS, MT)

    Sunday, March 14:
    +1 hour: Canada (except Saskatchewan (excluding western parts that are in
    Mountain Time) and the areas around Resolute (NU),
    Atikokan (ON) and Southampton Island (NU),
    Blanc-Sablon (PQ), and Dawson Creek and Fort Saint
    John (BC))
    United States (except Hawaii and most (non-Navajo areas) of
    Arizona)
    parts of Mexico near US border (except Sonora)
    Bahamas
    Bermuda
    Cuba
    Turks & Caicos Islands
    St. Pierre & Miquelon
    Thule area (Greenland)

    -1 hour: Uruguay
    San Luis area (Argentina)
    Palmer Station (Antarctica)

    Monday, March 22:
    +1 hour: Iran

    Friday, March 26:
    +1 hour: Jordan, Syria, Israel, Palestinian Territories

    Sunday, March 28:
    +1 hour: all of Europe (except Iceland and Georgia), including:
    all of Russia (except Novokuznetsk area)
    all of Turkey
    Armenia
    Azerbaijan
    Cyprus
    Faroe Islands
    Tunisia
    Lebanon
    most of Greenland (except Thule and Danmarkshavn areas)

    -1 hour: Samoa
    Fiji

    Thursday, April 1:
    +1 hour: Bangladesh

    Sunday, April 4:
    -1 hour: much of Australia (Victoria, NSW, Tasmania, SA, ACT?)
    New Zealand
    Namibia
    Chile
    McMurdo and Amundsen-Scott Stations (Antarctica)

    -0.5 hours: Lord Howe Island (Australia)

    +1 hour: Mexico (except Sonora and parts near US border)

    Sunday, April 11:
    -1 hour: Paraguay

    Thursday, April 15:
    +1 hour: Pakistan

    Sunday, April 18:
    -1 hour: Falkland Islands

    Friday, April 30:
    +1 hour: Egypt

    On second thought, don't bother posting DST correction announcements.
    The newsgroup would be flooded throughout late March and April, as well
    as a similar timeframe near the other equinox.


    --
    Beware of bugs in the above code; I have only proved it correct, not
    tried it. -- Donald E. Knuth
     
    Joshua Cranmer, Mar 17, 2010
    #6
  7. Roedy Green

    Roedy Green Guest

    On Mon, 15 Mar 2010 09:54:17 +0000, bugbear
    <bugbear@trim_papermule.co.uk_trim> wrote, quoted or indirectly quoted
    someone who said :

    >> Your computer should have automatically set your PC clock ahead 1 hour
    >> at 2AM this morning.

    >
    >No it shouldn't!


    I presume by that you mean the UTC time should not have shifted, just
    the displayed local time? Or that this only applies to Canada and the
    USA?
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 17, 2010
    #7
  8. Roedy Green

    Roedy Green Guest

    On Tue, 16 Mar 2010 13:24:12 +0000, Dr J R Stockton
    <> wrote, quoted or indirectly quoted
    someone who said :

    >Codswallop and balderdash. The proper date for that is the last Sunday
    >in March and the proper time is 01:00 UTC (or GMT), which all Canadians
    >should realise. The proper date to change back is the last Sunday in
    >October, at the same UTC.


    Not any more. Remember Mr. Bush extended the range of DST.

    The 2:00 AM local time rule is what I learned as a young child, and in
    general that is when public clocks change in my part of the world.

    What is your source for 1:00 UTC?
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 17, 2010
    #8
  9. Roedy Green

    Roedy Green Guest

    On Tue, 16 Mar 2010 13:24:12 +0000, Dr J R Stockton
    <> wrote, quoted or indirectly quoted
    someone who said :

    >
    >Codswallop and balderdash. The proper date for that is the last Sunday
    >in March and the proper time is 01:00 UTC (or GMT), which all Canadians
    >should realise. The proper date to change back is the last Sunday in
    >October, at the same UTC.



    according to TimeZone.inDaylightTime, for PST, the shift happened
    2010-03-14.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 17, 2010
    #9
  10. In comp.lang.java.programmer message <c5r0q516d182h35q6jsad1nk7hdl5iuv5t
    @4ax.com>, Tue, 16 Mar 2010 22:49:26, Roedy Green <see_website@mindprod.
    com.invalid> posted:
    >On Tue, 16 Mar 2010 13:24:12 +0000, Dr J R Stockton
    ><> wrote, quoted or indirectly quoted
    >someone who said :
    >
    >>Codswallop and balderdash. The proper date for that is the last Sunday
    >>in March and the proper time is 01:00 UTC (or GMT), which all Canadians
    >>should realise. The proper date to change back is the last Sunday in
    >>October, at the same UTC.

    >
    >Not any more. Remember Mr. Bush extended the range of DST.


    Mr Bush is, and was, irrelevant (and North America previously used the
    first Sunday in April). Moreover, while the Energy Policy Act of 2005
    applied throughout America, that part of the Act did not have effect
    throughout America. The States are not in all respects United. Neither
    is Canada; the Provinces decided independently to use the new days, but
    do not all change at the same local time - NRC has a Time FAQ.

    >The 2:00 AM local time rule is what I learned as a young child, and in
    >general that is when public clocks change in my part of the world.


    But you said nothing about your part of the world in your initial post.
    You wrote "Your computer should have automatically set your PC clock
    ahead 1 hour at 2AM this morning.". You were addressing a world-wide,
    if sparse, readership. The whole world does not revolve around your
    country's southern appendage. It generally agrees with what Churchill
    might have said about them.

    That sentence is full of error. There, "computer" should be plural; I
    have four - the one which runs DOS cannot alter its time; the correct
    time to change in Spring is 01:00 previous local (01:00 UTC or GMT); the
    correct date is the last Sunday in March ... and it's unreasonable to
    expect them to do anything at that sort of time, since they are all
    turned completely off, externally to themselves[*].

    >What is your source for 1:00 UTC?


    For such things, consult
    <URL:http://www.merlyn.demon.co.uk/uksumtim.htm>.
    The efficient source is The Summer Time Order 2002, of which there is a
    copy at <http://www.opsi.gov.uk/si/si2002/20020262.htm>. That is an
    Order of your Monarch, albeit not one aimed at you, implementing for the
    UK an EU Directive. One hopes that the Lord of Mann issued a similar
    order.


    [*] On general grounds, virtually every night; with special care to do
    so around local 00:59-02:01 on the last Sunday in March, and around
    local 00:59-02:01 on the last Sunday in October.

    --
    (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
    Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
    PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
    Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
     
    Dr J R Stockton, Mar 18, 2010
    #10
  11. Roedy Green

    Roedy Green Guest

    On Thu, 18 Mar 2010 20:31:57 +0000, Dr J R Stockton
    <> wrote, quoted or indirectly quoted
    someone who said :

    >
    >>The 2:00 AM local time rule is what I learned as a young child, and in
    >>general that is when public clocks change in my part of the world.


    National TV gave me the impression DST was informally implemented
    across Canada, with the exception of Saskatchewan who stick to "God's
    time". I was astounded to find out it is far from so.


    In most of Canada, DST begins and ends at 2 AM on the same days as the
    USA. However, in Newfoundland and Labrador, DST begins one minute
    after midnight local time on the second Sunday in March. On the first
    Sunday in November time returns to standard at one minute after
    midnight local time.

    A few areas of Canada don’t use DST at all including Fort St. John,
    Charlie Lake, Taylor and Dawson Creek, Creston in British Columbia,
    and most of Saskatchewan (except Denare Beach and Creighton).

    It seems so odd I could have visited Creston several times without
    noticing this.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 20, 2010
    #11
  12. Roedy Green

    Roedy Green Guest

    On Thu, 18 Mar 2010 20:31:57 +0000, Dr J R Stockton
    <> wrote, quoted or indirectly quoted
    someone who said :

    >and it's unreasonable to
    >expect them to do anything at that sort of time, since they are all
    >turned completely off, externally to themselves[*].


    PCs running recent versions of Windows adjust themselves just fine
    when you turn them back on. For the recent Windows, nothing happens to
    the CMOS clock, just to the software that displays the current value.

    If they are powered on, you can see them change (in my case) bang on
    at 2 AM).

    For XT-era, what happened depended on your proprietary clock driver.
    For AT-era, you had to manually set the clock forward and back an hour
    since the CMOS clock kept local time. An the OS was not prepared to do
    the sort of timezone bookkeeping that Java and Windows 7 do. What we
    do now was not really feasible without weekly Internet automatic
    updates to keep time zone tables up to date.

    DST is an idiotic idea that just complicates timekeeping and
    guarantees errors. I wonder how many people have died as a result of
    errors caused by DST. I wonder the aggregate cost of all the missed
    appointments.


    --
    Roedy Green Canadian Mind Products
    http://mindprod.com

    Responsible Development is the style of development I aspire to now. It can be summarized by answering the question, “How would I develop if it were my money?” I’m amazed how many theoretical arguments evaporate when faced with this question.
    ~ Kent Beck (born: 1961 age: 49) , evangelist for extreme programming.
     
    Roedy Green, Mar 20, 2010
    #12
  13. In comp.lang.java.programmer message <39GdnSt5Lps88T7WnZ2dnUVZ7odi4p2d@b
    rightview.co.uk>, Fri, 19 Mar 2010 12:22:57, bugbear <bugbear@trim_paper
    mule.co.uk_trim> posted:
    >Roedy Green wrote:
    >> On Mon, 15 Mar 2010 09:54:17 +0000, bugbear
    >> <bugbear@trim_papermule.co.uk_trim> wrote, quoted or indirectly quoted
    >> someone who said :
    >>
    >>>> Your computer should have automatically set your PC clock ahead 1
    >>>>hour
    >>>> at 2AM this morning.
    >>> No it shouldn't!

    >> I presume by that you mean the UTC time should not have shifted,
    >>just
    >> the displayed local time? Or that this only applies to Canada and the
    >> USA?

    >
    >The latter...


    Parts of the USA and parts of Canada do not use DST. Part of Canada
    changes at different times. Other parts of North America, apparently
    including Cuba, use the same date for at least one of the annual
    changes.

    Uruguay & Paraguay also change on 2 Sun Mar, but not as described.

    --
    (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
    Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
    PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
    Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
     
    Dr J R Stockton, Mar 20, 2010
    #13
  14. In comp.lang.java.programmer message <d7j9q553fncdn1sbvue4m086rri4v6ou6i
    @4ax.com>, Sat, 20 Mar 2010 06:35:06, Roedy Green <see_website@mindprod.
    com.invalid> posted:
    >On Thu, 18 Mar 2010 20:31:57 +0000, Dr J R Stockton
    ><> wrote, quoted or indirectly quoted
    >someone who said :
    >
    >>and it's unreasonable to
    >>expect them to do anything at that sort of time, since they are all
    >>turned completely off, externally to themselves[*].

    >
    >PCs running recent versions of Windows adjust themselves just fine
    >when you turn them back on.


    Of course. But that is different.

    > For the recent Windows, nothing happens to
    >the CMOS clock, just to the software that displays the current value.


    I have a 16-bit DOS program, INT-TEST via sig line 3, which tests
    various low-level things concerning date and time. In a week's time,
    I'll be able to test it in Summer Time in WinXP sp3 on P4/3G.

    It will be interesting to see what CMD.EXE and COMMAND.COM windows then
    show as the apparent behaviour of the CMOS clock. Feel free to try it!
    It should be enough to run it, then <cr>, then read the "Peep" line,
    then Q to quit.

    If the CMOS clock does not maintain local civil time, it ought to hold
    UTC; it seems half-measures to hold local standard (Winter) time,

    --
    (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
    Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
    PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
    Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
     
    Dr J R Stockton, Mar 21, 2010
    #14
  15. Roedy Green

    Tim Slattery Guest

    Roedy Green <> wrote:

    >In most of Canada, DST begins and ends at 2 AM on the same days as the
    >USA. However, in Newfoundland and Labrador, DST begins one minute
    >after midnight local time on the second Sunday in March. On the first
    >Sunday in November time returns to standard at one minute after
    >midnight local time.


    And remember that Newfoundland time is thirty minutes ahead of
    Atlantic time (Nova Scotia, etc). They're in their own world!

    --
    Tim Slattery

    http://members.cox.net/slatteryt
     
    Tim Slattery, Mar 22, 2010
    #15
  16. In comp.lang.java.programmer message <
    on.merlyn.invalid>, Sun, 21 Mar 2010 15:38:00, Dr J R Stockton
    <> posted:
    >In comp.lang.java.programmer message <d7j9q553fncdn1sbvue4m086rri4v6ou6i
    >@4ax.com>, Sat, 20 Mar 2010 06:35:06, Roedy Green <see_website@mindprod.
    >com.invalid> posted:
    >>On Thu, 18 Mar 2010 20:31:57 +0000, Dr J R Stockton
    >><> wrote, quoted or indirectly quoted
    >>someone who said :
    >>
    >>>and it's unreasonable to
    >>>expect them to do anything at that sort of time, since they are all
    >>>turned completely off, externally to themselves[*].

    >>
    >>PCs running recent versions of Windows adjust themselves just fine
    >>when you turn them back on.

    >
    >Of course. But that is different.
    >
    >> For the recent Windows, nothing happens to
    >>the CMOS clock, just to the software that displays the current value.

    >
    >I have a 16-bit DOS program, INT-TEST via sig line 3, which tests
    >various low-level things concerning date and time. In a week's time,
    >I'll be able to test it in Summer Time in WinXP sp3 on P4/3G.
    >
    >It will be interesting to see what CMD.EXE and COMMAND.COM windows then
    >show as the apparent behaviour of the CMOS clock. Feel free to try it!
    >It should be enough to run it, then <cr>, then read the "Peep" line,
    >then Q to quit.
    >
    >If the CMOS clock does not maintain local civil time, it ought to hold
    >UTC; it seems half-measures to hold local standard (Winter) time,



    It is now Summer Time here.

    Win XP sp3, both COMMAND.COM and CMD.EXE - the program says that both
    the RTC and the software DOS clock show UK civil time. Therefore, the
    apparent RTC has been put forward by an hour. I do not know what that
    proves, though.

    --
    (c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
    Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
    PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
    Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
     
    Dr J R Stockton, Mar 28, 2010
    #16
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