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diff --git a/doc/info/solar-python.texinfo b/doc/info/solar-python.texinfo new file mode 100644 index 0000000..b47a789 --- /dev/null +++ b/doc/info/solar-python.texinfo @@ -0,0 +1,551 @@ +\input texinfo @c -*-texinfo-*- + +@c %**start of header +@setfilename solar-python.info +@settitle solar-python +@afourpaper +@documentencoding UTF-8 +@documentlanguage en +@finalout +@c %**end of header + + +@dircategory Astronomy +@direntry +* solar-python: (solar-python). Solar data calculation and prediction library for Python +@end direntry + + +@copying +Copyright @copyright{} 2015 Mattias Andrée + +@quotation +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with no +Invariant Sections, with no Front-Cover Texts, and with no Back-Cover +Texts. A copy of the license is included in the section entitled +``GNU Free Documentation License''. +@end quotation +@end copying + +@ifnottex +@node Top +@top solar-python -- Solar data calculation and prediction library for Python +@insertcopying +@end ifnottex + +@titlepage +@title solar-python +@subtitle Solar data calculation and prediction library for Python +@author by Mattias Andrée (maandree) + +@page +@vskip 0pt plus 1filll +@insertcopying +@page +@end titlepage + +@contents + + + +@menu +* Overview:: Brief overview of @command{solar-python}. +* Constants:: List of constants. +* Calendar functions:: List of calendar functions. +* Observation functions:: List of solar data observation functions. +* Prediction functions:: List of solar data prediction functions. +* Miscellaneous functions:: List of miscellaneous functions. +* GNU Free Documentation License:: Copying and sharing this manual. +@end menu + + + +@node Overview +@chapter Overview + +@command{solar-python} is Python 3 library that can +be used to calculate information about the Sun's +position and related data and predict at when time +solar events occur. + +Import the module @code{solar_python} to use the +library. + +Documentation is available by the command @code{help} +in python. + + + +@node Constants +@chapter Constants + +Importing @code{solar_python} makes the following +constants available: + +@table @code +@item SOLAR_APPARENT_RADIUS = 32 / 60 +Approximate apparent size of the Sun in degrees. +@item SOLAR_ELEVATION_SUNSET_SUNRISE = 0.0 +The Sun's elevation at sunset and sunrise, measured +in degrees. +@item SOLAR_ELEVATION_CIVIL_DUSK_DAWN = -6.0 +The Sun's elevation at civil dusk and civil dawn, +measured in degrees +@item SOLAR_ELEVATION_NAUTICAL_DUSK_DAWN = -12.0 +The Sun's elevation at nautical dusk and nautical +dawn, measured in degrees +@item SOLAR_ELEVATION_ASTRONOMICAL_DUSK_DAWN = -18.0 +The Sun's elevation at astronomical dusk and +astronomical dawn, measured in degrees +@item SOLAR_ELEVATION_RANGE_TWILIGHT = (-18.0, 0.0) +The Sun's lowest and highest elevation during all +periods of twilight, measured in degrees +@item SOLAR_ELEVATION_RANGE_CIVIL_TWILIGHT = (-6.0, 0.0) +The Sun's lowest and highest elevation during +civil twilight, measured in degrees +@item SOLAR_ELEVATION_RANGE_NAUTICAL_TWILIGHT = (-12.0, -6.0) +The Sun's lowest and highest elevation during +nautical twilight, measured in degrees +@item SOLAR_ELEVATION_RANGE_ASTRONOMICAL_TWILIGHT = (-18.0, -12.0) +The Sun's lowest and highest elevation during +astronomical twilight, measured in degrees +@end table + + + +@node Calendar functions +@chapter Calendar functions + +Importing @code{solar_python} makes the following +calendar conversion functions available. All +parameters are of the type @code{float}, and +all functions return @code{float}. + +@table @code +@item julian_day_to_epoch(t) +Converts a Julian Day timestamp, @code{t}, to a POSIX time timestamp. +@item epoch_to_julian_day(t) +Converts a POSIX time timestamp, @code{t}, to a Julian Day timestamp +@item julian_day_to_julian_centuries(t) +Converts a Julian Day timestamp, @code{t}, to a Julian Centuries timestamp. +@item julian_centuries_to_julian_day(t) +Converts a Julian Centuries timestamp, @code{t}, to a Julian Day timestamp. +@item epoch_to_julian_centuries(t) +Converts a POSIX time timestamp, @code{t}, to a Julian Centuries timestamp. +@item julian_centuries_to_epoch(t) +Converts a Julian Centuries timestamp, @code{t}, to a POSIX time timestamp. +@end table + +@code{solar_python} also makes the following +functions available. All parameters are of the +type @code{float}, and all functions return +@code{float}. + +@table @code +@item epoch() +Get current POSIX time. +@item julian_day() +Get current Julian Day time. +@item julian_centuries() +Get current Julian Centuries time (100 Julian days since J2000.) +@end table + + + +@node Observation functions +@chapter Observation functions + +Importing @code{solar_python} makes the following +solar data observation functions available. All +parameters are of the type @code{float}, and +all functions return @code{float}. All parameters +named @code{t} or @code{noon} is the time in +Julian Centuries. These are low-level functions. + +@table @code +@item sun_geometric_mean_longitude(t) +Calculates the Sun's geometric mean longitude. +@item sun_geometric_mean_anomaly(t) +Calculates the Sun's geometric mean anomaly, in radians. +@item earth_orbit_eccentricity(t) +Calculates the Earth's orbit eccentricity. +@item sun_equation_of_centre(t) +Calculates the Sun's equation of the centre --- the +difference between the true anomaly and the mean +anomaly --- in radians. +@item sun_real_longitude(t) +Calculates the Sun's real longitudinal position, in radians. +@item sun_apparent_longitude(t) +Calculates the Sun's apparent longitudinal position, in radians. +@item mean_ecliptic_obliquity(t) +Calculates the uncorrected mean ecliptic obliquity of the Sun's +apparent motion without variation correction, in radians. +@item corrected_mean_ecliptic_obliquity(t) +Calculates the mean ecliptic obliquity of the Sun's apparent +motion with variation correction, in radians. +@item solar_declination(t) +Calculates the Sun's declination, in radians. +@item equation_of_time(t) +Calculates the equation of time --- the discrepancy +between apparent and mean solar time --- in degrees. +@item hour_angle_from_elevation(latitude, declination, elevation) +Calculates the solar hour angle, in radians, from the Sun's +elevation, in radians. The Sun's elevation is gived by the +parameter @code{elevation}. This functions requires two +additional parameters: +@table @code +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@item declination +The declination, in radians. +@end table +@item elevation_from_hour_angle(latitude, declination, hour_angle) +Calculates the Sun's elevation, in radians, from the solar +hour angle, in radians. The solar hour angle is gived by the +parameter @code{hour_angle}. This functions requires two +additional parameters: +@table @code +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@item declination +The declination, in radians. +@end table +@item time_of_solar_noon(t, longitude) +Calculates the time, in Julian Centuries, of the solar +noon the closest to the time @code{t}. This functions +requires one additional parameter: +@table @code +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@end table +@item time_of_solar_elevation(t, noon, latitude, longitude, elevation) +Calculates the time, in Julian Centuries, the Sun has +a specified apparent elevation, expressed in radians +via the parameter @code{elevation}, at a geographical +position, expressed in degrees by the parameters: +@table @code +@item latitude +The latitude in degrees northwards from the equator, +negative for southwards. +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@end table +@noindent +The function require two additional parameter: +@table @code +@item t +A time, in Julian Centuries, close to the sought time. +@item noon +The time, in Julian Centuries, of the closest solar noon. +@end table +@item solar_elevation_from_time(t, latitude, longitude): +Calculates the Sun's elevation, in radians, as apparent +from a geographical position, expressed in degrees by the +parameters: +@table @code +@item latitude +The latitude in degrees northwards from the equator, +negative for southwards. +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@end table +@end table + +The library also provides the high-level functions: +@table @code +@item solar_elevation(latitude, longitude, t = None) +Calculates the Sun's elevation, in degreesm as apparent +from a geographical position, expressed in degrees by the parameters: +@table @code +@item latitude +The latitude in degrees northwards from the equator, +negative for southwards. +@item longitude +The longitude in degrees eastwards from Greenwich, +negative for westwards. +@end table +@noindent +The function also requires to the in Julian Centuries, +provided via the parameter @code{t}. If @code{t} is +@code{None}, the current time is used. +@item have_sunrise_and_sunset(latitude, t = None) +Determine whether solar declination currently is +so that there can be sunrises and sunsets. If not, +you either have 24-hour daytime or 24-hour nighttime. +The function requires to the in Julian Centuries, +provided via the parameter @code{t}, and the latitude, +provided via the parameter @code{latitude}, in degrees +northwards from the equator, negative for southwards. +If @code{t} is @code{None}, the current time is used. + +@item is_summer(latitude, t = None) +Determine whether it is summer on the hemisphere +ont which you are located. +The function requires to the in Julian Centuries, +provided via the parameter @code{t}, and the latitude, +provided via the parameter @code{latitude}, in degrees +northwards from the equator, negative for southwards. +If @code{t} is @code{None}, the current time is used. + +@item is_winter(latitude, t = None) +Determine whether it is winter on the hemisphere +ont which you are located. +The function requires to the in Julian Centuries, +provided via the parameter @code{t}, and the latitude, +provided via the parameter @code{latitude}, in degrees +northwards from the equator, negative for southwards. +If @code{t} is @code{None}, the current time is used. +@end table + + + +@node Prediction functions +@chapter Prediction functions + + + +@node Miscellaneous functions +@chapter Miscellaneous functions + +Importing @code{solar_python} makes the following +functions available: +@table @code +@item radians(deg): +Convert an angle from degrees to radians. +@item degrees(rad): +Convert an angle from radians to degrees. +@end table + + + +@node GNU Free Documentation License +@appendix GNU Free Documentation License +@include fdl.texinfo + +@bye + + + + + +----------------------------- Prediction functions ----------------------------- + +def solar_prediction(delta, requested, fun, epsilon = 0.000001, span = 0.01, t = None): + ''' + Predict the time point of the next or previous + time an arbitrary condition is meet + + @param delta:float Iteration step size, negative for past + event, positive for future event + @param requested:float The value returned by `fun` for which to + calculate the time point of occurrence + @param fun:(t:float)→float Function that calculate the data of interest + @param epsilon:float Error tolerance for `requested` + @param span:float The number of Julian centuries (0,01 for + one year) to restrict the search to + @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 the specified time span + ''' + +def future_past_equinox(delta, t = None): + ''' + Predict the time point of the next or previous equinox + + @param delta:float Iteration step size, negative for + past event, positive for future event + @param t:float? The time in Julian Centuries, `None` + for the current time + @return :float The calculated time point + ''' + return solar_prediction(delta, 0, solar_declination, t = t) + + +def future_equinox(t = None): + ''' + Predict the time point of the next equinox + + @param t:float? The time in Julian Centuries, `None` + for the current time + @return :float The calculated time point + ''' + return future_past_equinox(0.01 / 2000, t) + + +def past_equinox(t = None): + ''' + Predict the time point of the previous equinox + + @param t:float? The time in Julian Centuries, `None` + for the current time + @return :float The calculated time point + ''' + return future_past_equinox(0.01 / -2000, t) + + + +def future_past_solstice(delta, t = None): + ''' + Predict the time point of the next or previous solstice + + @param delta:float Iteration step size, negative for + past event, positive for future event + @param t:float? The time in Julian Centuries, `None` + for the current time + @return :float The calculated time point + ''' + e = 0.00001 + fun = solar_declination + dfun = lambda t : (fun(t + e) - fun(t - e)) / 2 + return solar_prediction(delta, 0, dfun, t = t) + + +def future_solstice(t = None): + ''' + Predict the time point of the next solstice + + @param t:float? The time in Julian Centuries, + `None` for the current time + @return :float The calculated time point + ''' + return future_past_solstice(0.01 / 2000, t) + + +def past_solstice(t = None): + ''' + Predict the time point of the previous solstice + + @param t:float? The time in Julian Centuries, + `None` for the current time + @return :float The calculated time point + ''' + return future_past_solstice(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 + + @param delta:float Iteration step size, negative for past + event, positive for future event + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @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 + ''' + fun = lambda t : solar_elevation(latitude, longitude, t) + return solar_prediction(delta, elevation, fun, t = t) + + +def future_elevation(latitude, longitude, elevation, t = None): + ''' + Predict the time point of the next time the Sun + reaches a specific elevation + + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @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) + + +def past_elevation(latitude, longitude, elevation, t = None): + ''' + Predict the time point of the previous time the Sun + reached a specific elevation + + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @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) + + + +def future_past_elevation_derivative(delta, latitude, longitude, derivative, t = None): + ''' + Predict the time point of the next or previous time the + Sun reaches or reached a specific elevation derivative + + @param delta:float Iteration step size, negative for past + event, positive for future event + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @param longitude:float The longitude in degrees eastwards from + Greenwich, negative for westwards + @param derivative:float The elevation derivative value 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 + ''' + fun = lambda t : solar_elevation(latitude, longitude, t) + dfun = lambda t : (fun(t + e) - fun(t - e)) / 2 + return solar_prediction(delta, derivative, dfun, t = t) + + +def future_elevation_derivative(latitude, longitude, derivative, t = None): + ''' + Predict the time point of the next time the + Sun reaches a specific elevation derivative + + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @param longitude:float The longitude in degrees eastwards from + Greenwich, negative for westwards + @param derivative:float The elevation derivative value 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_derivative(0.01 / 2000, latitude, longitude, derivative, t) + + +def past_elevation_derivative(latitude, longitude, derivative, t = None): + ''' + Predict the time point of the previous time + the Sun reached a specific elevation derivative + + @param latitude:float The latitude in degrees northwards from + the equator, negative for southwards + @param longitude:float The longitude in degrees eastwards from + Greenwich, negative for westwards + @param derivative:float The elevation derivative value 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_derivative(0.01 / -2000, latitude, longitude, derivative, t) + + +# This algorithm is imprecise, gives an incorrent sunrise and I do not fully know its behaviour +def sunrise_equation(latitude, longitude, t = None): |