Drop BigDecimal

[rhannequin]

BigDecimal was introduced early in the project from my belief that high accuracy was needed.

It turns out that the number of digits in floats are enough to keep a precision up to 0.0001 arcseconds in most calculations.

Using BigDecimal has a cost over the overall performance of the library. If it is not absolutely necessary for the calculations, it's better not to use it. Calculations are performed 11 times faster using only floats, for the same precision (see benchmark below).

Benchmark

The benchmark simply executes usual calculations enabled by the library at the moment, many times.

Benchmark.bmbm do |x|
  x.report do
    10_000.times do
      time = Time.utc(2023, 2, 17, 11, 0, 0)
      epoch = Astronoby::Epoch.from_time(time)

      observer = Astronoby::Observer.new(
        latitude: Astronoby::Angle.from_degrees(38),
        longitude: Astronoby::Angle.from_degrees(-78)
      )

      sun = Astronoby::Sun.new(epoch: epoch)

      sun
        .apparent_ecliptic_coordinates
        .to_apparent_equatorial(epoch: epoch)
        .to_horizontal(
          time: time,
          latitude: observer.latitude,
          longitude: observer.longitude
        )

      sun.rising_time(observer: observer)
      sun.rising_azimuth(observer: observer).str(:dms)
      sun.setting_time(observer: observer)
      sun.setting_azimuth(observer: observer).str(:dms)

      year = 2024
      Astronoby::EquinoxSolstice.march_equinox(year)
      Astronoby::EquinoxSolstice.june_solstice(year)
    end
  end
end

                         user    system      total         real
with BigDecimal     61.342663  0.351669  61.694332  (61.892873)
without BigDecimal   5.286487  0.004743   5.291230   (5.308093)