bose 0.1.4

A library of mathematical and scientific formulas
Documentation 
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//! Geography

/// Location struct
pub struct Location {
    /// latitude of the location
    pub latitude: f64,
    /// longitude of the location
    pub longitude: f64,
}

/// Enum for unit of distance
pub enum Unit {
    /// miles
    Mile,
    /// kilometers
    Kilometer,
}

/// Example
///
/// ```rust
/// let radian = bose::geography::to_radian(10.0);
/// assert_eq!(radian, 0.17453292519943295);
/// ```
pub fn to_radian(number: f64) -> f64 {
    return number.to_radians();
}

/// Example
///
/// ```rust
/// let haversine_distance_in_miles = bose::geography::distance(
/// 	bose::geography::Location {
/// 		latitude: 48.85341,
/// 		longitude: -2.34880,
/// 	},
/// 	bose::geography::Location {
/// 		latitude: 51.50853,
/// 		longitude: -0.12574,
/// 	},
/// 	bose::geography::Unit::Mile,
/// );
/// assert_eq!(haversine_distance_in_miles, 194.5908231787244);
///
/// let haversine_distance_in_kilometers = bose::geography::distance(
/// 	bose::geography::Location {
/// 		latitude: 48.85341,
/// 		longitude: -2.34880,
/// 	},
/// 	bose::geography::Location {
/// 		latitude: 51.50853,
/// 		longitude: -0.12574,
/// 	},
/// 	bose::geography::Unit::Kilometer,
/// );
/// assert_eq!(haversine_distance_in_kilometers, 313.0651854726397);
/// ```
pub fn distance(start: Location, end: Location, unit: Unit) -> f64 {
    let earth_radius_in_kilometers: f64 = 6371.0;
    let earth_radius_in_miles: f64 = 3960.0;
    let mut earth_radius: f64 = 0.0;

    match unit {
        Unit::Mile => earth_radius = earth_radius_in_miles,
        Unit::Kilometer => earth_radius = earth_radius_in_kilometers,
    }

    let start_latitude_in_radians: f64 = (start.latitude).to_radians();
    let end_latitude_in_radians: f64 = (end.latitude).to_radians();

    let delta_latitude: f64 = (end.latitude - start.latitude).to_radians();
    let delta_longitude: f64 = (end.longitude - start.longitude).to_radians();

    let central_angle_inner: f64 = ((delta_latitude / 2.0).sin()) * ((delta_longitude / 2.0).sin())
        + ((delta_longitude / 2.0).sin())
            * ((delta_longitude / 2.0).sin())
            * (start_latitude_in_radians.cos())
            * (end_latitude_in_radians.cos());

    let central_angle: f64 =
        2.0 * ((central_angle_inner.sqrt()).atan2((1.0 - central_angle_inner).sqrt()));

    return earth_radius * central_angle;
}