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Diffstat (limited to '')
| -rw-r--r-- | src/solar.py | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/solar.py b/src/solar.py index 55a325a..da02c6c 100644 --- a/src/solar.py +++ b/src/solar.py @@ -462,6 +462,53 @@ def is_winter(latitude, t = None): return not ((d > 0) == (latitude > 0)) +# TODO document and demo +def future_past_equinox(delta, t = None): + epsilon = 0.000001 + t = julian_centuries() if t is None else t + t1 = t2 = t + d1 = d0 = solar_declination(t) + while True: + if abs(t2 - t) > 0.01: + return None + t2 += delta + d2 = solar_declination(t2) + if (d1 <= 0 <= d2) or ((0 >= d1 >= d2) and (0 <= d0)): + break + if (d1 >= 0 >= d2) or ((0 <= d1 <= d2) and (0 >= d0)): + break + t1 = t2 + d2 = d1 + for _itr in range(1000): + tm = (t1 + t2) / 2 + d1 = solar_declination(t1) + d2 = solar_declination(t2) + dm = solar_declination(tm) + if abs(d1 - d2) < epsilon: + return tm if abs(dm) < epsilon else None + if d1 < d2: + if 0 < dm: + t2 = tm + else: + t1 = tm + elif d1 > d2: + if 0 > dm: + t2 = tm + else: + t1 = tm + return None + + +# TODO document and demo +def future_equinox(t = None): + return future_past_equinox(0.01 / 2000, t) + + +# TODO document and demo +def past_equinox(t = None): + return future_past_equinox(0.01 / -2000, t) + + def future_past_elevation(delta, latitude, longitude, elevation, t = None): ''' Predict the time point of the next or previous time the Sun reaches or reached a specific elevation @@ -471,6 +518,7 @@ def future_past_elevation(delta, latitude, longitude, elevation, t = None): @param longitude:float The longitude in degrees eastwards from Greenwich, negative for westwards @param elevation:float The elevation of interest @param t:float? The time in Julian Centuries, `None` for the current time + @return :float The calculated time point, `None` if none were found within a year ''' epsilon = 0.000001 t = julian_centuries() if t is None else t @@ -515,6 +563,7 @@ def future_elevation(latitude, longitude, elevation, t = None): @param longitude:float The longitude in degrees eastwards from Greenwich, negative for westwards @param elevation:float The elevation of interest @param t:float? The time in Julian Centuries, `None` for the current time + @return :float The calculated time point, `None` if none were found within a year ''' return future_past_elevation(0.01 / 2000, latitude, longitude, elevation, t) @@ -527,6 +576,7 @@ def past_elevation(latitude, longitude, elevation, t = None): @param longitude:float The longitude in degrees eastwards from Greenwich, negative for westwards @param elevation:float The elevation of interest @param t:float? The time in Julian Centuries, `None` for the current time + @return :float The calculated time point, `None` if none were found within a year ''' return future_past_elevation(0.01 / -2000, latitude, longitude, elevation, t) |