8 releases (4 breaking)
0.5.1 | Feb 11, 2024 |
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0.5.0 | Feb 11, 2024 |
0.4.0 | Jun 11, 2023 |
0.3.1 | Apr 18, 2023 |
0.1.1 | Nov 19, 2017 |
#42 in Date and time
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Used in 2 crates
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Solar Position Algorithm (SPA)
The Solar Position Algorithm module (SPA) for Rust calculates the sunrise-sunset and azimuth and zenith-angle for specific geo-position and time (UTC); for example for solar-panel-alignment or automotive.
Calculating the Sunrise and Sunset
The following function is calculating the sunrise-sunset at geo-pos lat/lon
at time t
(UTC).
The algorithm has been ported to Rust from http://lexikon.astronomie.info/zeitgleichung/neu.html Its accuracy is in the range of a few minutes.
Arguments
utc
- UTC time-point (DateTime)lat
- latitude in WGS84 system, ranging from -90.0 to 90.0.lon
- longitude in WGS84 system, ranging from -180.0 to 180.0
The function returns a result of type SunriseAndSet
.
pub enum SunriseAndSet {
PolarNight,
PolarDay,
Daylight(DateTime<Utc>, DateTime<Utc>),
}
The polar night occurs in the northernmost and southernmost regions of the Earth when the night lasts
for more than 24 hours. This occurs only inside the polar circles. The opposite phenomenon, the
polar day, or midnight sun, occurs when the Sun stays above the horizon for more than 24 hours.
"Night" is understood as the center of the Sun being below a free horizon, represented by the variants
SunriseAndSet::PolarNight
or SunriseAndSet::PolarDay
.
Since the atmosphere bends the rays of the Sun, the polar day is longer than the polar night, and the area that is affected by polar night is somewhat smaller than the area of midnight sun. The polar circle is located at a latitude between these two areas, at the latitude of approximately 66.5 degrees. The function is approximating the atmospheric bend using a height of 0,833333 degrees.
The variant SunriseAndSet::Daylight(DateTime<Utc>, DateTime<Utc>)
represents time of sunrise and sunset.
In case latitude or longitude are not in valid ranges, the function will return Result::Err(BadParam)
.
pub fn sunrise_and_set<F: FloatOps>(utc: DateTime<Utc>, lat: f64, lon: f64) -> Result<SunriseAndSet, SpaError> {..}
Calculating the Solar Position
The following functions is calculating the solar position (azimuth and zenith-angle)
at time t
and geo-pos lat/lon
The algorithm has been ported to Rust from http://www.psa.es/sdg/sunpos.htm The algorithm is accurate to within 0.5 minutes of arc for the year 1999 and following.
Arguments
utc
- UTC time-point (DateTime)lat
- latitude in WGS84 system, ranging from -90.0 to 90.0.lon
- longitude in WGS84 system, ranging from -180.0 to 180.0
The function returns a result of type SolarPos
.
pub struct SolarPos {
// horizontal angle measured clockwise from a north base line or meridian
pub azimuth: f64,
// the angle between the zenith and the centre of the sun's disc
pub zenith_angle: f64,
}
In case latitude or longitude are not in valid ranges, the function will return Result::Err(BadParam)
.
pub fn solar_position<F: FloatOps>(utc: DateTime<Utc>, lat: f64, lon: f64) -> Result<SolarPos, SpaError> {..}
Platform specific Float Operations
The SPA library supports both std
and no_std
target builds via the FloatOps
trait:
pub trait FloatOps {
fn sin(x: f64) -> f64;
fn cos(x: f64) -> f64;
fn tan(x: f64) -> f64;
fn asin(x: f64) -> f64;
fn acos(x: f64) -> f64;
fn atan(x: f64) -> f64;
fn atan2(y: f64, x: f64) -> f64;
fn trunc(x: f64) -> f64;
}
- On
std
target builds (default), the built-in implementationStdFloatOps
is provided for your convenience, gated behind thestd
feature.
[dependencies]
spa = "^0.5"
- On
no_std
target builds, you need to provide your own implementation for floating point operations, for example using libm. Thedefault-features = false
option must be specified in a dependency declaration.
[dependencies]
spa = { version = "^0.5", default-features = false }
Dependencies
~1–1.3MB
~20K SLoC