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Fixed #187 - Seasons() fixes from kotlin branch.

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Backported fixes to the Seasons functions in
C, C#, Python, and JavaScript. They were failing
to find equinoxes and/or solstices for distant
year values.

Also brought over some other minor code cleanup.
This commit is contained in:
Don Cross
2022-04-08 18:18:45 -04:00
parent 94eabbd4a9
commit 0c4e3dfec3
28 changed files with 391 additions and 245 deletions
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19
source/python/astronomy/astronomy.py
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@@ -5642,7 +5642,7 @@ def SearchSunLongitude(targetLon, startTime, limitDays):
Time or `None`
"""
t2 = startTime.AddDays(limitDays)
return Search(_sun_offset, targetLon, startTime, t2, 1.0)
return Search(_sun_offset, targetLon, startTime, t2, 0.01)
def MoonPhase(time):
"""Returns the Moon's phase as an angle from 0 to 360 degrees.
@@ -6444,7 +6444,7 @@ class SeasonInfo:
def _FindSeasonChange(targetLon, year, month, day):
startTime = Time.Make(year, month, day, 0, 0, 0)
time = SearchSunLongitude(targetLon, startTime, 4.0)
time = SearchSunLongitude(targetLon, startTime, 20.0)
if time is None:
# We should always be able to find a season change.
raise InternalError()
@@ -6486,10 +6486,17 @@ def Seasons(year):
-------
SeasonInfo
"""
mar_equinox = _FindSeasonChange(0, year, 3, 19)
jun_solstice = _FindSeasonChange(90, year, 6, 19)
sep_equinox = _FindSeasonChange(180, year, 9, 21)
dec_solstice = _FindSeasonChange(270, year, 12, 20)
# https://github.com/cosinekitty/astronomy/issues/187
# Solstices and equinoxes drift over long spans of time,
# due to precession of the Earth's axis.
# Therefore, we have to search a wider range of time than
# one might expect. It turns out this has very little
# effect on efficiency, thanks to the quick convergence
# of quadratic interpolation inside the `Search` function.
mar_equinox = _FindSeasonChange( 0, year, 3, 10)
jun_solstice = _FindSeasonChange( 90, year, 6, 10)
sep_equinox = _FindSeasonChange(180, year, 9, 10)
dec_solstice = _FindSeasonChange(270, year, 12, 10)
return SeasonInfo(mar_equinox, jun_solstice, sep_equinox, dec_solstice)
def _MoonDistance(time):