Module: When::TimeStandard

Included in:
TimeStandard
Defined in:
lib/when_exe/timestandard.rb,
lib/when_exe/region/martian.rb

Overview

標準的な時刻系の定義

Defined Under Namespace

Modules: TimeBasis Classes: LocalApparentTime, LocalMeanTime, MartianTimeCoordinated, TemporalHourSystem, TimeStandard, UniversalTime

Constant Summary collapse

DeltaT0 =

TT(Terrestrial Time) - UTC(Universal Time, Coordinated) at 1970-01-01T00:00:00Z

(40 + 377.0/2048) * When::TM::Duration::SECOND
TAI_UTC =

maia.usno.navy.mil/ser7/tai-utc.dat

[[2437300.5,  1.422818, 37300.0, 0.001296 ],
[2437512.5,  1.372818, 37300.0, 0.001296 ],
[2437665.5,  1.845858, 37665.0, 0.0011232],
[2438334.5,  1.945858, 37665.0, 0.0011232],
[2438395.5,  3.24013,  38761.0, 0.001296 ],
[2438486.5,  3.34013,  38761.0, 0.001296 ],
[2438639.5,  3.44013,  38761.0, 0.001296 ],
[2438761.5,  3.54013,  38761.0, 0.001296 ],
[2438820.5,  3.64013,  38761.0, 0.001296 ],
[2438942.5,  3.74013,  38761.0, 0.001296 ],
[2439004.5,  3.84013,  38761.0, 0.001296 ],
[2439126.5,  4.31317,  39126.0, 0.002592 ],
[2439887.5,  4.21317,  39126.0, 0.002592 ],
[2441317.5, 10.0],
[2441499.5, 11.0],
[2441683.5, 12.0],
[2442048.5, 13.0],
[2442413.5, 14.0],
[2442778.5, 15.0],
[2443144.5, 16.0],
[2443509.5, 17.0],
[2443874.5, 18.0],
[2444239.5, 19.0],
[2444786.5, 20.0],
[2445151.5, 21.0],
[2445516.5, 22.0],
[2446247.5, 23.0],
[2447161.5, 24.0],
[2447892.5, 25.0],
[2448257.5, 26.0],
[2448804.5, 27.0],
[2449169.5, 28.0],
[2449534.5, 29.0],
[2450083.5, 30.0],
[2450630.5, 31.0],
[2451179.5, 32.0],
[2453736.5, 33.0],
[2454832.5, 34.0],
[2456109.5, 35.0]]
DeltaT =

1999

[                                                                63.467, # 1999
   63.827, 64.092, 64.300, 64.473, 64.573, 64.689, 64.846, 65.145, 65.456, 65.779, # 2000-
   66.070, 66.324, 66.603, 66.909                                                  # 2010-
]
YearThreshold = 
1997.0 + DeltaT.size
DeltaThreshold = 
DeltaT[-2] - delta_t_observed_poly(YearThreshold)

Class Method Summary collapse

Class Method Details

._is_systemtime_universal? ⇒ Boolean

処理系が閏秒を無視しているか否か

Returns:

  • (Boolean) 


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# File 'lib/when_exe/timestandard.rb', line 102

def _is_systemtime_universal?
  @is_systemtime_universal = ((Time.utc(1976).to_i - Time.utc(1975).to_i) % 86400 == 0) if @is_systemtime_universal == nil
  @is_systemtime_universal
end

._leap_seconds ⇒ Object

閏秒の挿入記録を取得する



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# File 'lib/when_exe/timestandard.rb', line 96

def _leap_seconds
  @leap_seconds ||= TAI_UTC.reverse
end

._setup_(leap_seconds = nil) ⇒ void

Note:

本メソッドでマルチスレッド対応の管理変数の初期化を行っている。 このため、本メソッド自体はスレッドセーフでない。

This method returns an undefined value.

When::TimeStandard Module のグローバルな設定を行う

Parameters:

  • leap_seconds (String) (defaults to: nil) —

    maia.usno.navy.mil/ser7/tai-utc.dat 形式のファイルのファイルパス

  • leap_seconds (Array<Array<Numeric>>) (defaults to: nil) —

    閏秒の挿入記録 [ [ JD, TAI-UTC, (MJD, OFFSET) ] ]

    JD - 閏秒を挿入した日時のユリウス日
    TAI-UTC - 閏秒を挿入後の TAI と UTC の差
    MJD - 周波数オフセットの基準となる日時の修正ユリウス日
    OFFSET - 周波数オフセット値 


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# File 'lib/when_exe/timestandard.rb', line 78

def _setup_(leap_seconds=nil)
  @_lock_ = Mutex.new if When.multi_thread
  leap_seconds ||= TAI_UTC
  @leap_seconds  =
    if leap_seconds.kind_of?(String)
      OpenURI
      open(leap_seconds) do |file|
        file.read.split(/[\n\r]+/).map { |line|
          line.split(/[^\d.]+/)[3..6].map {|d| d.to_f}
        }.reverse
      end
    else
      leap_seconds.reverse
    end
end

.delta_t(jd_utc) ⇒ Numeric Also known as: deltaT

ΔT

Parameters:

  • jd_utc (Numeric) —

    ユリウス日(Universal Time, Coordinated)

Returns:

  • (Numeric) —

    (dynamical_time - universal_time) / second 1/2048 second(≒0.5ms)未満を四捨五入



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# File 'lib/when_exe/timestandard.rb', line 114

def delta_t(jd_utc)
  (delta_t_coordinated(jd_utc) * 4096 + 1).floor / 4096.0
end

.delta_t_coordinated(jd_utc) ⇒ Numeric

ΔT - 閏秒による(TT-UTC)

Parameters:

  • jd_utc (Numeric) —

    ユリウス日(Universal Time, Coordinated)

Returns:

  • (Numeric) —

    (Terrestrial Time - Universal Time, Coordinated) / second



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# File 'lib/when_exe/timestandard.rb', line 125

def delta_t_coordinated(jd_utc)
  list = _leap_seconds
  list.each do |v|
    if jd_utc >= v[0]
      result  = 32.184 + v[1]
      result += (jd_utc - (2400000.5 + v[2])) * v[3] unless (v[3]||0) == 0
      return result
    end
  end
  delta_t_observed(jd_utc)
end

.delta_t_observed(jd_utc) ⇒ Numeric

ΔT - 観測による(TT-UT1) mix of Table and NASA

Parameters:

  • jd_utc (Numeric) —

    ユリウス日(Universal Time, Coordinated)

Returns:

  • (Numeric) —

    (Terrestrial Time - Universal Time 1) / second



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# File 'lib/when_exe/timestandard.rb', line 143

def delta_t_observed(jd_utc)
  year = (jd_utc - When::Ephemeris::EPOCH2000)/When::Ephemeris::JYEAR + 2000 # 0年からの経過世紀
  return delta_t_observed_poly(year) unless 2000 <= year && year < 2050
  return delta_t_observed_poly(year) + DeltaThreshold * (year - 2050.0) / (YearThreshold - 2050.0) if year >= YearThreshold

  i = (year-1999.0).floor             # 1999年からの経過年(整数)
  n    = year % 1
  d0   = DeltaT[i+0] - DeltaT[i-1]
  d1   = DeltaT[i+1] - DeltaT[i+0]
  d2   = DeltaT[i+2] - DeltaT[i+1]
  d10  = d1  - d0
  d21  = d2  - d1
  d210 = d21 - d10
  DeltaT[i] + n*d1 + n*(n-1.0)/4.0*(d10+d21) + n*(n-1.0)*(n-0.5)/6.0*d210
end

.delta_t_observed_nasa(jd_utc) ⇒ Numeric

ΔT - 観測による(TT-UT1) from eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html

Parameters:

  • jd_utc (Numeric) —

    ユリウス日(Universal Time, Coordinated)

Returns:

  • (Numeric) —

    (Terrestrial Time - Universal Time 1) / second



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# File 'lib/when_exe/timestandard.rb', line 165

def delta_t_observed_nasa(jd_utc)
  delta_t_observed_poly((jd_utc - When::Ephemeris::EPOCH2000)/When::Ephemeris::JYEAR + 2000.0) # 0年からの経過年
end

.delta_t_observed_poly(year) ⇒ Object

多項式による近似



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# File 'lib/when_exe/timestandard.rb', line 170

def delta_t_observed_poly(year)
  u    = (year-1820)/100

  # 2150 ... 3000
  if    year >= 2150
    -20 + 32 * u**2

  # 2050 ... 2150
  elsif year >= 2050
    -20 + 32 * u**2 - 0.5628 * (2150 - year)

  # 2005 ... 2050
  elsif year >= 2005
    t = year - 2000
    62.92 + 0.32217 * t + 0.005589 * t**2

  # 1986 ... 2005
  elsif year >= 1986
    t = year - 2000
    63.86 + 0.3345 * t - 0.060374 * t**2 + 0.0017275 * t**3 + 0.000651814 * t**4 + 0.00002373599 * t**5

  # 1961 ... 1986
  elsif year >= 1961
    t = year - 1975
   45.45 + 1.067*t - t**2/260 - t**3 / 718

  # 1941 ... 1961
  elsif year >= 1941
    t = year - 1950
    29.07 + 0.407*t - t**2/233 + t**3 / 2547

  # 1920 ... 1941
  elsif year >= 1920
    t = year - 1920
    21.20 + 0.84493*t - 0.076100 * t**2 + 0.0020936 * t**3

  # 1900 ... 1920
  elsif year >= 1900
    t = year - 1900
     -2.79 + 1.494119 * t - 0.0598939 * t**2 + 0.0061966 * t**3 - 0.000197 * t**4

  # 1860 ... 1900
  elsif year >= 1860
    t = year - 1860
     7.62 + 0.5737 * t - 0.251754 * t**2 + 0.01680668 * t**3 - 0.0004473624 * t**4 + t**5 / 233174

  # 1800 ... 1860
  elsif year >= 1800
    t = year - 1800
    13.72 - 0.332447 * t + 0.0068612 * t**2 + 0.0041116 * t**3 - 0.00037436 * t**4 + 0.0000121272 * t**5 - 0.0000001699 * t**6 + 0.000000000875 * t**7

  # 1700 ... 1800
  elsif year >= 1700
    t = year - 1700
    8.83 + 0.1603 * t - 0.0059285 * t**2 + 0.00013336 * t**3 - t**4 / 1174000

  # 1600 ... 1700
  elsif year >= 1600
    t = year - 1600
    120 - 0.9808 * t - 0.01532 * t**2 + t**3 / 7129

  # 500 ... 1600
  elsif year >=  500
    u = (year - 1000) / 100
    1574.2 - 556.01 * u + 71.23472 * u**2 + 0.319781 * u**3 - 0.8503463 * u**4 - 0.005050998 * u**5 + 0.0083572073 * u**6

  # -500 ... 500
  elsif year >= -500
    u = year / 100
    10583.6 - 1014.41 * u + 33.78311 * u**2 - 5.952053 * u**3 - 0.1798452 * u**4 + 0.022174192 * u**5 + 0.0090316521 * u**6

  # ... -500
  else
    -20 + 32 * u**2
  end
end

.from_dynamical_time(time) ⇒ Numeric

dynamical time を universal time に変換する

Parameters:

  • time (Numeric) —

    dynamical time

Returns:



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# File 'lib/when_exe/timestandard.rb', line 266

def from_dynamical_time(time)
  return time unless -Float::MAX/4 < time && time < Float::MAX/4
  jd_tt = When::TM::JulianDate._t_to_d(time)
  utc   = time - delta_t(jd_tt) * When::TM::Duration::SECOND
  diff  = time - to_dynamical_time(utc)
  return utc if diff == 0 # 間に閏秒なし
  utc  += diff
  diff  = time - to_dynamical_time(utc)
  return utc if diff == 0 # 間に閏秒なし
  return When::Coordinates::LeapSeconds.new(utc+diff, -diff, When::TM::Duration::SECOND)
end

.from_time_object(time) ⇒ Numeric

Time オブジェクトを dynamical time に変換する

Parameters:

Returns:



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# File 'lib/when_exe/timestandard.rb', line 284

def from_time_object(time)
  time = time.to_f * When::TM::Duration::SECOND
  _is_systemtime_universal? ? to_dynamical_time(time) : time + DeltaT0
end

.to_dynamical_time(time) ⇒ Numeric

universal time を dynamical time に変換する

Parameters:

  • time (Numeric) —

    universal time

Returns:



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# File 'lib/when_exe/timestandard.rb', line 254

def to_dynamical_time(time)
  return time unless -Float::MAX/4 < time && time < Float::MAX/4
  jd_utc = When::TM::JulianDate._t_to_d(time * 1)
  +time + delta_t(jd_utc) * When::TM::Duration::SECOND
end

.to_time_object(time) ⇒ ::Time

dynamical time を Time オブジェクトに変換する

Parameters:

  • time (Numeric) —

    dynamical time

Returns:



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# File 'lib/when_exe/timestandard.rb', line 295

def to_time_object(time)
  time = _is_systemtime_universal? ? from_dynamical_time(time) : time - DeltaT0
  ::Time.at(+time / When::TM::Duration::SECOND)
end