Method: When::Ephemeris::Datum#axis_of_rotation

Defined in:

lib/when_exe/ephemeris.rb

#axis_of_rotation(t) ⇒ When::Ephemeris::Coords

自転軸の歳差補正

Parameters:

• t (Numeric) —

  ユリウス日(Terrestrial Time)

• t (When::TM::TemporalPosition)

Returns:

• (When::Ephemeris::Coords)

# File 'lib/when_exe/ephemeris.rb', line 1043

def axis_of_rotation(t)
  return nil unless @axis
  c1900 = (@axis[0]-1900.0)/100.0
  dt    = (+t-(EPOCH1900-0.68648354))/BCENT - c1900
  Coords.polar(
    (@axis[1][0] + dt * @axis[2][0]) / 360,
    (@axis[1][1] + dt * @axis[2][1]) / 360,
    (@axis[1][2] + dt * @axis[2][2]) / 360
  ).precession(dt, c1900)
end