def approx_moment_of_depression(self, tee, alpha, early):
"""Return the moment in local time near tee when depression angle
of sun is alpha (negative if above horizon) at location;
early is true when MORNING event is sought and false for EVENING.
Raise VlueError if depression angle is not reached."""
ttry = self.sine_offset(tee, alpha)
date = Clock.fixed_from_moment(tee)
if alpha >= 0:
if early:
alt = date
else:
alt = date + 1
else:
alt = date + Clock.days_from_hours(12)
if abs(ttry) > 1:
value = self.sine_offset(alt, alpha)
else:
value = ttry
if abs(value) <= 1:
temp = -1 if early else 1
temp *= mod(Clock.days_from_hours(12) + arcsin_degrees(value) / 360, 1) - Clock.days_from_hours(6)
temp += date + Clock.days_from_hours(12)
return self.local_from_apparent(temp)
else:
raise ValueError("Depression angle not reached")
def hindu_tithi_occur(l_month, tithi, tee, l_year):
"""Return the fixed date of occurrence of Hindu lunar tithi prior
to sundial time, tee, in Hindu lunar month, l_month, and
year, l_year."""
approx = hindu_date_occur(l_month, ifloor(tithi), l_year)
lunar = HinduLunarDate.day_at_or_after(tithi, approx - 2)
ttry = Clock.fixed_from_moment(lunar)
tee_h = HinduLunarDate.UJJAIN.standard_from_sundial(ttry + tee)
if lunar <= tee_h or HinduLunarDate.lunar_phase(HinduLunarDate.UJJAIN.standard_from_sundial(ttry + 1 + tee)) > 12 * tithi:
return ttry
else:
return ttry + 1
def standard_from_sundial(self, tee):
"""Return standard time of temporal moment, tee, at location, location."""
date = Clock.fixed_from_moment(tee)
hour = 24 * mod(tee, 1)
if 6 <= hour <= 18:
h = self.daytime_temporal_hour(date)
elif (hour < 6):
h = self.nighttime_temporal_hour(date - 1)
else:
h = self.nighttime_temporal_hour(date)
# return
if 6 <= hour <= 18:
return self.sunrise(date) + ((hour - 6) * h)
elif hour < 6:
return self.sunset(date - 1) + ((hour + 6) * h)
else:
return self.sunset(date) + ((hour - 18) * h)
def sundial_time(cls, tee):
"""Return Hindu local time of temporal moment, tee."""
date = Clock.fixed_from_moment(tee)
time = mod(tee, 1)
q = ifloor(4 * time)
if q == 0:
a = cls.sunset(date - 1)
b = cls.sunrise(date)
t = Clock.days_from_hours(-6)
elif q == 3:
a = cls.sunset(date)
b = cls.sunrise(date + 1)
t = Clock.days_from_hours(18)
else:
a = cls.sunrise(date)
b = cls.sunset(date)
t = Clock.days_from_hours(6)
return a + (2 * (b - a) * (time - t))
