Struct Duration 

pub struct Duration { /* private fields */ }

Defines generally usable durations for nanosecond precision valid for 32,768 centuries in either direction, and only on 80 bits / 10 octets.

Important conventions:

1. The negative durations can be mentally modeled “BC” years. One hours before 01 Jan 0000, it was “-1” years but 365 days and 23h into the current day. It was decided that the nanoseconds corresponds to the nanoseconds into the current century. In other words, a duration with centuries = -1 and nanoseconds = 0 is a greater duration (further from zero) than centuries = -1 and nanoseconds = 1. Duration zero minus one nanosecond returns a century of -1 and a nanosecond set to the number of nanoseconds in one century minus one. That difference is exactly 1 nanoseconds, where the former duration is “closer to zero” than the latter. As such, the largest negative duration that can be represented sets the centuries to i16::MAX and its nanoseconds to NANOSECONDS_PER_CENTURY.
2. It was also decided that opposite durations are equal, e.g. -15 minutes == 15 minutes. If the direction of time matters, use the signum function.

(Python documentation hints) :type string_repr: str

Implementations

impl Duration

pub const ZERO: Duration

A duration of exactly zero nanoseconds

pub const MAX: Duration

Maximum duration that can be represented

pub const MIN: Duration

Minimum duration that can be represented

pub const EPSILON: Duration

Smallest duration that can be represented

pub const MIN_POSITIVE: Duration = Self::EPSILON

Minimum positive duration is one nanoseconds

pub const MIN_NEGATIVE: Duration

Minimum negative duration is minus one nanosecond

pub const fn from_parts(centuries: i16, nanoseconds: u64) -> Duration

Create a normalized duration from its parts

pub const fn from_total_nanoseconds(nanos: i128) -> Duration

Converts the total nanoseconds as i128 into this Duration (saving 48 bits)

pub const fn from_truncated_nanoseconds(nanos: i64) -> Duration

Create a new duration from the truncated nanoseconds (+/- 2927.1 years of duration)

pub const fn from_days(value: f64) -> Duration

Creates a new duration from the provided number of days

pub const fn from_hours(value: f64) -> Duration

Creates a new duration from the provided number of hours

pub const fn from_seconds(value: f64) -> Duration

Creates a new duration from the provided number of seconds

pub const fn from_milliseconds(value: f64) -> Duration

Creates a new duration from the provided number of milliseconds

pub const fn from_microseconds(value: f64) -> Duration

Creates a new duration from the provided number of microsecond

pub const fn from_nanoseconds(value: f64) -> Duration

Creates a new duration from the provided number of nanoseconds

pub fn compose( sign: i8, days: u64, hours: u64, minutes: u64, seconds: u64, milliseconds: u64, microseconds: u64, nanoseconds: u64, ) -> Duration

Creates a new duration from its parts. Set the sign to a negative number for the duration to be negative.

pub fn compose_f64( sign: i8, days: f64, hours: f64, minutes: f64, seconds: f64, milliseconds: f64, microseconds: f64, nanoseconds: f64, ) -> Duration

Creates a new duration from its parts. Set the sign to a negative number for the duration to be negative.

pub fn from_tz_offset(sign: i8, hours: i64, minutes: i64) -> Duration

Initializes a Duration from a timezone offset

impl Duration

pub const fn to_parts(&self) -> (i16, u64)

Returns the centuries and nanoseconds of this duration NOTE: These items are not public to prevent incorrect durations from being created by modifying the values of the structure directly.

pub fn total_nanoseconds(&self) -> i128

Returns the total nanoseconds in a signed 128 bit integer

pub fn try_truncated_nanoseconds(&self) -> Result<i64, HifitimeError>

Returns the truncated nanoseconds in a signed 64 bit integer, if the duration fits.

pub fn truncated_nanoseconds(&self) -> i64

Returns the truncated nanoseconds in a signed 64 bit integer, if the duration fits. WARNING: This function will NOT fail and will return the i64::MIN or i64::MAX depending on the sign of the centuries if the Duration does not fit on aa i64

pub fn to_seconds(&self) -> f64

Returns this duration in seconds f64. For high fidelity comparisons, it is recommended to keep using the Duration structure.

Examples found in repository

examples/03_geo_analysis/drift.rs (line 172)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the orbit.
    // First we need to fetch the Earth J2000 from information from the Almanac.
    // This allows the frame to include the gravitational parameters and the shape of the Earth,
    // defined as a tri-axial ellipoid. Note that this shape can be changed manually or in the Almanac
    // by loading a different set of planetary constants.
    let earth_j2000 = almanac.frame_info(EARTH_J2000)?;

    // Placing this GEO bird just above Colorado.
    // In theory, the eccentricity is zero, but in practice, it's about 1e-5 to 1e-6 at best.
    let orbit = Orbit::try_keplerian(42164.0, 1e-5, 0., 163.0, 75.0, 0.0, epoch, earth_j2000)?;
    // Print in in Keplerian form.
    println!("{orbit:x}");

    let state_bf = almanac.transform_to(orbit, IAU_EARTH_FRAME, None)?;
    let (orig_lat_deg, orig_long_deg, orig_alt_km) = state_bf.latlongalt()?;

    // Nyx is used for high fidelity propagation, not Keplerian propagation as above.
    // Nyx only propagates Spacecraft at the moment, which allows it to account for acceleration
    // models such as solar radiation pressure.

    // Let's build a cubesat sized spacecraft, with an SRP area of 10 cm^2 and a mass of 9.6 kg.
    let sc = Spacecraft::builder()
        .orbit(orbit)
        .mass(Mass::from_dry_mass(9.60))
        .srp(SRPData {
            area_m2: 10e-4,
            coeff_reflectivity: 1.1,
        })
        .build();
    println!("{sc:x}");

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics_21x21 = Harmonics::from_stor(
        almanac.frame_info(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 21, 21, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics_21x21);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth and Moon.
    let srp_dyn = SolarPressure::new(vec![EARTH_J2000, MOON_J2000], almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Finally, let's propagate this orbit to the same epoch as above.
    // The first returned value is the spacecraft state at the final epoch.
    // The second value is the full trajectory where the step size is variable step used by the propagator.
    let (future_sc, trajectory) = Propagator::default(dynamics)
        .with(sc, almanac.clone())
        .until_epoch_with_traj(epoch + Unit::Century * 0.03)?;

    println!("=== High fidelity propagation ===");
    println!(
        "SMA changed by {:.3} km",
        orbit.sma_km()? - future_sc.orbit.sma_km()?
    );
    println!(
        "ECC changed by {:.6}",
        orbit.ecc()? - future_sc.orbit.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_sc.orbit.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3} deg",
        orbit.raan_deg()? - future_sc.orbit.raan_deg()?
    );
    println!(
        "AOP changed by {:.3} deg",
        orbit.aop_deg()? - future_sc.orbit.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_sc.orbit.ta_deg()?
    );

    // We also have access to the full trajectory throughout the propagation.
    println!("{trajectory}");

    println!("Spacecraft params after 3 years without active control:\n{future_sc:x}");

    // With the trajectory, let's build a few data products.

    // 1. Export the trajectory as a parquet file, which includes the Keplerian orbital elements.

    let analysis_step = Unit::Minute * 5;

    trajectory.to_parquet(
        "./03_geo_hf_prop.parquet",
        ExportCfg::builder().step(analysis_step).build(),
    )?;

    // 2. Compute the latitude, longitude, and altitude throughout the trajectory by rotating the spacecraft position into the Earth body fixed frame.

    // We iterate over the trajectory, grabbing a state every two minutes.
    let mut offset_s = vec![];
    let mut epoch_str = vec![];
    let mut longitude_deg = vec![];
    let mut latitude_deg = vec![];
    let mut altitude_km = vec![];

    for state in trajectory.every(analysis_step) {
        // Convert the GEO bird state into the body fixed frame, and keep track of its latitude, longitude, and altitude.
        // These define the GEO stationkeeping box.

        let this_epoch = state.epoch();

        offset_s.push((this_epoch - orbit.epoch).to_seconds());
        epoch_str.push(this_epoch.to_isoformat());

        let state_bf = almanac.transform_to(state.orbit, IAU_EARTH_FRAME, None)?;
        let (lat_deg, long_deg, alt_km) = state_bf.latlongalt()?;
        longitude_deg.push(long_deg);
        latitude_deg.push(lat_deg);
        altitude_km.push(alt_km);
    }

    println!(
        "Longitude changed by {:.3} deg -- Box is 0.1 deg E-W",
        orig_long_deg - longitude_deg.last().unwrap()
    );

    println!(
        "Latitude changed by {:.3} deg -- Box is 0.05 deg N-S",
        orig_lat_deg - latitude_deg.last().unwrap()
    );

    println!(
        "Altitude changed by {:.3} km -- Box is 30 km",
        orig_alt_km - altitude_km.last().unwrap()
    );

    // Build the station keeping data frame.
    let mut sk_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch (UTC)" => epoch_str.clone(),
        "Longitude E-W (deg)" => longitude_deg,
        "Latitude N-S (deg)" => latitude_deg,
        "Altitude (km)" => altitude_km,

    )?;

    // Create a file to write the Parquet to
    let file = File::create("./03_geo_lla.parquet").expect("Could not create file");

    // Create a ParquetWriter and write the DataFrame to the file
    ParquetWriter::new(file).finish(&mut sk_df)?;

    Ok(())
}

examples/01_orbit_prop/main.rs (line 227)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the orbit.
    // First we need to fetch the Earth J2000 from information from the Almanac.
    // This allows the frame to include the gravitational parameters and the shape of the Earth,
    // defined as a tri-axial ellipoid. Note that this shape can be changed manually or in the Almanac
    // by loading a different set of planetary constants.
    let earth_j2000 = almanac.frame_info(EARTH_J2000)?;

    let orbit =
        Orbit::try_keplerian_altitude(300.0, 0.015, 68.5, 65.2, 75.0, 0.0, epoch, earth_j2000)?;
    // Print in in Keplerian form.
    println!("{orbit:x}");

    // There are two ways to propagate an orbit. We can make a quick approximation assuming only two-body
    // motion. This is a useful first order approximation but it isn't used in real-world applications.

    // This approach is a feature of ANISE.
    let future_orbit_tb = orbit.at_epoch(epoch + Unit::Day * 3)?;
    println!("{future_orbit_tb:x}");

    // Two body propagation relies solely on Kepler's laws, so only the true anomaly will change.
    println!(
        "SMA changed by {:.3e} km",
        orbit.sma_km()? - future_orbit_tb.sma_km()?
    );
    println!(
        "ECC changed by {:.3e}",
        orbit.ecc()? - future_orbit_tb.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_orbit_tb.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3e} deg",
        orbit.raan_deg()? - future_orbit_tb.raan_deg()?
    );
    println!(
        "AOP changed by {:.3e} deg",
        orbit.aop_deg()? - future_orbit_tb.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_orbit_tb.ta_deg()?
    );

    // Nyx is used for high fidelity propagation, not Keplerian propagation as above.
    // Nyx only propagates Spacecraft at the moment, which allows it to account for acceleration
    // models such as solar radiation pressure.

    // Let's build a cubesat sized spacecraft, with an SRP area of 10 cm^2 and a mass of 9.6 kg.
    let sc = Spacecraft::builder()
        .orbit(orbit)
        .mass(Mass::from_dry_mass(9.60))
        .srp(SRPData {
            area_m2: 10e-4,
            coeff_reflectivity: 1.1,
        })
        .build();
    println!("{sc:x}");

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics_21x21 = Harmonics::from_stor(
        almanac.frame_info(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 21, 21, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics_21x21);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth.
    let srp_dyn = SolarPressure::default(EARTH_J2000, almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Finally, let's propagate this orbit to the same epoch as above.
    // The first returned value is the spacecraft state at the final epoch.
    // The second value is the full trajectory where the step size is variable step used by the propagator.
    let (future_sc, trajectory) = Propagator::default(dynamics)
        .with(sc, almanac.clone())
        .until_epoch_with_traj(future_orbit_tb.epoch)?;

    println!("=== High fidelity propagation ===");
    println!(
        "SMA changed by {:.3} km",
        orbit.sma_km()? - future_sc.orbit.sma_km()?
    );
    println!(
        "ECC changed by {:.6}",
        orbit.ecc()? - future_sc.orbit.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_sc.orbit.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3} deg",
        orbit.raan_deg()? - future_sc.orbit.raan_deg()?
    );
    println!(
        "AOP changed by {:.3} deg",
        orbit.aop_deg()? - future_sc.orbit.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_sc.orbit.ta_deg()?
    );

    // We also have access to the full trajectory throughout the propagation.
    println!("{trajectory}");

    // With the trajectory, let's build a few data products.

    // 1. Export the trajectory as a CCSDS OEM version 2.0 file and as a parquet file, which includes the Keplerian orbital elements.

    trajectory.to_oem_file(
        "./01_cubesat_hf_prop.oem",
        ExportCfg::builder().step(Unit::Minute * 2).build(),
    )?;

    trajectory.to_parquet_with_cfg(
        "./01_cubesat_hf_prop.parquet",
        ExportCfg::builder().step(Unit::Minute * 2).build(),
    )?;

    // 2. Compare the difference in the radial-intrack-crosstrack frame between the high fidelity
    // and Keplerian propagation. The RIC frame is commonly used to compute the difference in position
    // and velocity of different spacecraft.
    // 3. Compute the azimuth, elevation, range, and range-rate data of that spacecraft as seen from Boulder, CO, USA.

    let boulder_station = GroundStation::from_point(
        "Boulder, CO, USA".to_string(),
        40.014984,   // latitude in degrees
        -105.270546, // longitude in degrees
        1.6550,      // altitude in kilometers
        almanac.frame_info(IAU_EARTH_FRAME)?,
    );

    // We iterate over the trajectory, grabbing a state every two minutes.
    let mut offset_s = vec![];
    let mut epoch_str = vec![];
    let mut ric_x_km = vec![];
    let mut ric_y_km = vec![];
    let mut ric_z_km = vec![];
    let mut ric_vx_km_s = vec![];
    let mut ric_vy_km_s = vec![];
    let mut ric_vz_km_s = vec![];

    let mut azimuth_deg = vec![];
    let mut elevation_deg = vec![];
    let mut range_km = vec![];
    let mut range_rate_km_s = vec![];
    for state in trajectory.every(Unit::Minute * 2) {
        // Try to compute the Keplerian/two body state just in time.
        // This method occasionally fails to converge on an appropriate true anomaly
        // from the mean anomaly. If that happens, we just skip this state.
        // The high fidelity and Keplerian states diverge continuously, and we're curious
        // about the divergence in this quick analysis.
        let this_epoch = state.epoch();
        match orbit.at_epoch(this_epoch) {
            Ok(tb_then) => {
                offset_s.push((this_epoch - orbit.epoch).to_seconds());
                epoch_str.push(format!("{this_epoch}"));
                // Compute the two body state just in time.
                let ric = state.orbit.ric_difference(&tb_then)?;
                ric_x_km.push(ric.radius_km.x);
                ric_y_km.push(ric.radius_km.y);
                ric_z_km.push(ric.radius_km.z);
                ric_vx_km_s.push(ric.velocity_km_s.x);
                ric_vy_km_s.push(ric.velocity_km_s.y);
                ric_vz_km_s.push(ric.velocity_km_s.z);

                // Compute the AER data for each state.
                let aer = almanac.azimuth_elevation_range_sez(
                    state.orbit,
                    boulder_station.to_orbit(this_epoch, &almanac)?,
                    None,
                    None,
                )?;
                azimuth_deg.push(aer.azimuth_deg);
                elevation_deg.push(aer.elevation_deg);
                range_km.push(aer.range_km);
                range_rate_km_s.push(aer.range_rate_km_s);
            }
            Err(e) => warn!("{} {e}", state.epoch()),
        };
    }

    // Build the data frames.
    let ric_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch" => epoch_str.clone(),
        "RIC X (km)" => ric_x_km,
        "RIC Y (km)" => ric_y_km,
        "RIC Z (km)" => ric_z_km,
        "RIC VX (km/s)" => ric_vx_km_s,
        "RIC VY (km/s)" => ric_vy_km_s,
        "RIC VZ (km/s)" => ric_vz_km_s,
    )?;

    println!("RIC difference at start\n{}", ric_df.head(Some(10)));
    println!("RIC difference at end\n{}", ric_df.tail(Some(10)));

    let aer_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch" => epoch_str.clone(),
        "azimuth (deg)" => azimuth_deg,
        "elevation (deg)" => elevation_deg,
        "range (km)" => range_km,
        "range rate (km/s)" => range_rate_km_s,
    )?;

    // Finally, let's see when the spacecraft is visible, assuming 15 degrees minimum elevation.
    let mask = aer_df
        .column("elevation (deg)")?
        .gt(&Column::Scalar(ScalarColumn::new(
            "elevation mask (deg)".into(),
            Scalar::new(DataType::Float64, AnyValue::Float64(15.0)),
            offset_s.len(),
        )))?;
    let cubesat_visible = aer_df.filter(&mask)?;

    println!("{cubesat_visible}");

    Ok(())
}

pub fn to_unit(&self, unit: Unit) -> f64

pub fn abs(&self) -> Duration

Returns the absolute value of this duration

Examples found in repository

examples/04_lro_od/main.rs (line 344)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();

    // ====================== //
    // === ALMANAC SET UP === //
    // ====================== //

    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's MetaAlmanac.

    let data_folder: PathBuf = [env!("CARGO_MANIFEST_DIR"), "examples", "04_lro_od"]
        .iter()
        .collect();

    let meta = data_folder.join("lro-dynamics.dhall");

    // Load this ephem in the general Almanac we're using for this analysis.
    let mut almanac = MetaAlmanac::new(meta.to_string_lossy().as_ref())
        .map_err(Box::new)?
        .process(true)
        .map_err(Box::new)?;

    let mut moon_pc = almanac.get_planetary_data_from_id(MOON).unwrap();
    moon_pc.mu_km3_s2 = 4902.74987;
    almanac.set_planetary_data_from_id(MOON, moon_pc).unwrap();

    let mut earth = almanac.get_planetary_data_from_id(EARTH).unwrap();
    earth.mu_km3_s2 = 398600.436;
    almanac.set_planetary_data_from_id(EARTH, earth).unwrap();

    // Save this new kernel for reuse.
    // In an operational context, this would be part of the "Lock" process, and should not change throughout the mission.
    almanac
        .planetary_data
        .values()
        .next()
        .unwrap()
        .save_as(&data_folder.join("lro-specific.pca"), true)?;

    // Lock the almanac (an Arc is a read only structure).
    let almanac = Arc::new(almanac);

    // Orbit determination requires a Trajectory structure, which can be saved as parquet file.
    // In our case, the trajectory comes from the BSP file, so we need to build a Trajectory from the almanac directly.
    // To query the Almanac, we need to build the LRO frame in the J2000 orientation in our case.
    // Inspecting the LRO BSP in the ANISE GUI shows us that NASA has assigned ID -85 to LRO.
    let lro_frame = Frame::from_ephem_j2000(-85);

    // To build the trajectory we need to provide a spacecraft template.
    let sc_template = Spacecraft::builder()
        .mass(Mass::from_dry_and_prop_masses(1018.0, 900.0)) // Launch masses
        .srp(SRPData {
            // SRP configuration is arbitrary, but we will be estimating it anyway.
            area_m2: 3.9 * 2.7,
            coeff_reflectivity: 0.96,
        })
        .orbit(Orbit::zero(MOON_J2000)) // Setting a zero orbit here because it's just a template
        .build();
    // Now we can build the trajectory from the BSP file.
    // We'll arbitrarily set the tracking arc to 24 hours with a five second time step.
    let traj_as_flown = Traj::from_bsp(
        lro_frame,
        MOON_J2000,
        almanac.clone(),
        sc_template,
        5.seconds(),
        Some(Epoch::from_str("2024-01-01 00:00:00 UTC")?),
        Some(Epoch::from_str("2024-01-02 00:00:00 UTC")?),
        Aberration::LT,
        Some("LRO".to_string()),
    )?;

    println!("{traj_as_flown}");

    // ====================== //
    // === MODEL MATCHING === //
    // ====================== //

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Earth and the Sun.
    // The gravity of the Moon will also be accounted for since the spaceraft in a lunar orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![EARTH, SUN, JUPITER_BARYCENTER]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the GRAIL JGGRX model.
    let mut jggrx_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/Luna_jggrx_1500e_sha.tab.gz".to_string(),
        crc32: Some(0x6bcacda8), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jggrx_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Moon principal axes frame.
    let moon_pa_frame = MOON_PA_FRAME.with_orient(31008);
    let sph_harmonics = Harmonics::from_stor(
        almanac.frame_info(moon_pa_frame)?,
        HarmonicsMem::from_shadr(&jggrx_meta.uri, 80, 80, true)?,
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(sph_harmonics);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth and Moon.
    // Note that by default, enabling the SolarPressure model will also enable the estimation of the coefficient of reflectivity.
    let srp_dyn = SolarPressure::new(vec![EARTH_J2000, MOON_J2000], almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Now we can build the propagator.
    let setup = Propagator::default_dp78(dynamics.clone());

    // For reference, let's build the trajectory with Nyx's models from that LRO state.
    let (sim_final, traj_as_sim) = setup
        .with(*traj_as_flown.first(), almanac.clone())
        .until_epoch_with_traj(traj_as_flown.last().epoch())?;

    println!("SIM INIT:  {:x}", traj_as_flown.first());
    println!("SIM FINAL: {sim_final:x}");
    // Compute RIC difference between SIM and LRO ephem
    let sim_lro_delta = sim_final
        .orbit
        .ric_difference(&traj_as_flown.last().orbit)?;
    println!("{traj_as_sim}");
    println!(
        "SIM v LRO - RIC Position (m): {:.3}",
        sim_lro_delta.radius_km * 1e3
    );
    println!(
        "SIM v LRO - RIC Velocity (m/s): {:.3}",
        sim_lro_delta.velocity_km_s * 1e3
    );

    traj_as_sim.ric_diff_to_parquet(
        &traj_as_flown,
        "./data/04_output/04_lro_sim_truth_error.parquet",
        ExportCfg::default(),
    )?;

    // ==================== //
    // === OD SIMULATOR === //
    // ==================== //

    // After quite some time trying to exactly match the model, we still end up with an oscillatory difference on the order of 150 meters between the propagated state
    // and the truth LRO state.

    // Therefore, we will actually run an estimation from a dispersed LRO state.
    // The sc_seed is the true LRO state from the BSP.
    let sc_seed = *traj_as_flown.first();

    // Load the Deep Space Network ground stations.
    // Nyx allows you to build these at runtime but it's pretty static so we can just load them from YAML.
    let ground_station_file: PathBuf = [
        env!("CARGO_MANIFEST_DIR"),
        "examples",
        "04_lro_od",
        "dsn-network.yaml",
    ]
    .iter()
    .collect();

    let devices = GroundStation::load_named(ground_station_file)?;

    let mut proc_devices = devices.clone();

    // Increase the noise in the devices to accept more measurements.
    for gs in proc_devices.values_mut() {
        if let Some(noise) = &mut gs
            .stochastic_noises
            .as_mut()
            .unwrap()
            .get_mut(&MeasurementType::Range)
        {
            *noise.white_noise.as_mut().unwrap() *= 3.0;
        }
    }

    // Typical OD software requires that you specify your own tracking schedule or you'll have overlapping measurements.
    // Nyx can build a tracking schedule for you based on the first station with access.
    let trkconfg_yaml: PathBuf = [
        env!("CARGO_MANIFEST_DIR"),
        "examples",
        "04_lro_od",
        "tracking-cfg.yaml",
    ]
    .iter()
    .collect();

    let configs: BTreeMap<String, TrkConfig> = TrkConfig::load_named(trkconfg_yaml)?;

    // Build the tracking arc simulation to generate a "standard measurement".
    let mut trk = TrackingArcSim::<Spacecraft, GroundStation>::with_seed(
        devices.clone(),
        traj_as_flown.clone(),
        configs,
        123, // Set a seed for reproducibility
    )?;

    trk.build_schedule(almanac.clone())?;
    let arc = trk.generate_measurements(almanac.clone())?;
    // Save the simulated tracking data
    arc.to_parquet_simple("./data/04_output/04_lro_simulated_tracking.parquet")?;

    // We'll note that in our case, we have continuous coverage of LRO when the vehicle is not behind the Moon.
    println!("{arc}");

    // Now that we have simulated measurements, we'll run the orbit determination.

    // ===================== //
    // === OD ESTIMATION === //
    // ===================== //

    let sc = SpacecraftUncertainty::builder()
        .nominal(sc_seed)
        .frame(LocalFrame::RIC)
        .x_km(0.5)
        .y_km(0.5)
        .z_km(0.5)
        .vx_km_s(5e-3)
        .vy_km_s(5e-3)
        .vz_km_s(5e-3)
        .build();

    // Build the filter initial estimate, which we will reuse in the filter.
    let mut initial_estimate = sc.to_estimate()?;
    initial_estimate.covar *= 3.0;

    println!("== FILTER STATE ==\n{sc_seed:x}\n{initial_estimate}");

    // Build the SNC in the Moon J2000 frame, specified as a velocity noise over time.
    let process_noise = ProcessNoise3D::from_velocity_km_s(
        &[1e-10, 1e-10, 1e-10],
        1 * Unit::Hour,
        10 * Unit::Minute,
        None,
    );

    println!("{process_noise}");

    // We'll set up the OD process to reject measurements whose residuals are move than 3 sigmas away from what we expect.
    let odp = SpacecraftKalmanOD::new(
        setup,
        KalmanVariant::ReferenceUpdate,
        Some(ResidRejectCrit::default()),
        proc_devices,
        almanac.clone(),
    )
    .with_process_noise(process_noise);

    let od_sol = odp.process_arc(initial_estimate, &arc)?;

    let final_est = od_sol.estimates.last().unwrap();

    println!("{final_est}");

    let ric_err = traj_as_flown
        .at(final_est.epoch())?
        .orbit
        .ric_difference(&final_est.orbital_state())?;
    println!("== RIC at end ==");
    println!("RIC Position (m): {:.3}", ric_err.radius_km * 1e3);
    println!("RIC Velocity (m/s): {:.3}", ric_err.velocity_km_s * 1e3);

    println!(
        "Num residuals rejected: #{}",
        od_sol.rejected_residuals().len()
    );
    println!(
        "Percentage within +/-3: {}",
        od_sol.residual_ratio_within_threshold(3.0).unwrap()
    );
    println!("Ratios normal? {}", od_sol.is_normal(None).unwrap());

    od_sol.to_parquet(
        "./data/04_output/04_lro_od_results.parquet",
        ExportCfg::default(),
    )?;

    // Create the ephemeris
    let ephem = od_sol.to_ephemeris("LRO rebuilt".to_string());
    let ephem_start = ephem.start_epoch().unwrap();
    let ephem_end = ephem.end_epoch().unwrap();
    // Check that the covariance is PSD throughout the ephemeris by interpolating it.
    for epoch in TimeSeries::inclusive(ephem_start, ephem_end, Unit::Minute * 5) {
        ephem
            .covar_at(
                epoch,
                anise::ephemerides::ephemeris::LocalFrame::RIC,
                &almanac,
            )
            .unwrap_or_else(|e| panic!("covar not PSD at {epoch}: {e}"));
    }
    // Export as BSP!
    ephem
        .write_spice_bsp(-85, "./data/04_output/04_lro_rebuilt.bsp", None)
        .expect("could not built BSP");
    let new_almanac = Almanac::default()
        .load("./data/04_output/04_lro_rebuilt.bsp")
        .unwrap();
    new_almanac.describe(None, None, None, None, None, None, None, None);
    let (spk_start, spk_end) = new_almanac.spk_domain(-85).unwrap();

    assert!((ephem_start - spk_start).abs() < Unit::Microsecond * 1);
    assert!((ephem_end - spk_end).abs() < Unit::Microsecond * 1);

    // In our case, we have the truth trajectory from NASA.
    // So we can compute the RIC state difference between the real LRO ephem and what we've just estimated.
    // Export the OD trajectory first.
    let od_trajectory = od_sol.to_traj()?;
    // Build the RIC difference.
    od_trajectory.ric_diff_to_parquet(
        &traj_as_flown,
        "./data/04_output/04_lro_od_truth_error.parquet",
        ExportCfg::default(),
    )?;

    Ok(())
}

pub const fn signum(&self) -> i8

Returns the sign of this duration

• 0 if the number is zero
• 1 if the number is positive
• -1 if the number is negative

pub fn decompose(&self) -> (i8, u64, u64, u64, u64, u64, u64, u64)

Decomposes a Duration in its sign, days, hours, minutes, seconds, ms, us, ns

pub fn subdivision(&self, unit: Unit) -> Option<Duration>

Returns the subdivision of duration in this unit, if such is available. Does not work with Week or Century.

Example

use hifitime::{Duration, TimeUnits, Unit};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.subdivision(Unit::Hour), Some(2.hours()));
assert_eq!(two_hours_three_min.subdivision(Unit::Minute), Some(3.minutes()));
assert_eq!(two_hours_three_min.subdivision(Unit::Second), Some(Duration::ZERO));
assert_eq!(two_hours_three_min.subdivision(Unit::Week), None);

pub fn floor(&self, duration: Duration) -> Duration

Floors this duration to the closest duration from the bottom

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.floor(1.hours()), 2.hours());
assert_eq!(two_hours_three_min.floor(30.minutes()), 2.hours());
// This is zero because we floor by a duration longer than the current duration, rounding it down
assert_eq!(two_hours_three_min.floor(4.hours()), 0.hours());
assert_eq!(two_hours_three_min.floor(1.seconds()), two_hours_three_min);
assert_eq!(two_hours_three_min.floor(1.hours() + 1.minutes()), 2.hours() + 2.minutes());
assert_eq!(two_hours_three_min.floor(1.hours() + 5.minutes()), 1.hours() + 5.minutes());

pub fn ceil(&self, duration: Duration) -> Duration

Ceils this duration to the closest provided duration

This simply floors then adds the requested duration

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.ceil(1.hours()), 3.hours());
assert_eq!(two_hours_three_min.ceil(30.minutes()), 2.hours() + 30.minutes());
assert_eq!(two_hours_three_min.ceil(4.hours()), 4.hours());
assert_eq!(two_hours_three_min.ceil(1.seconds()), two_hours_three_min + 1.seconds());
assert_eq!(two_hours_three_min.ceil(1.hours() + 5.minutes()), 2.hours() + 10.minutes());

pub fn round(&self, duration: Duration) -> Duration

Rounds this duration to the closest provided duration

This performs both a ceil and floor and returns the value which is the closest to current one.

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.round(1.hours()), 2.hours());
assert_eq!(two_hours_three_min.round(30.minutes()), 2.hours());
assert_eq!(two_hours_three_min.round(4.hours()), 4.hours());
assert_eq!(two_hours_three_min.round(1.seconds()), two_hours_three_min);
assert_eq!(two_hours_three_min.round(1.hours() + 5.minutes()), 2.hours() + 10.minutes());

pub fn approx(&self) -> Duration

Rounds this duration to the largest units represented in this duration.

This is useful to provide an approximate human duration. Under the hood, this function uses round, so the “tipping point” of the rounding is half way to the next increment of the greatest unit. As shown below, one example is that 35 hours and 59 minutes rounds to 1 day, but 36 hours and 1 minute rounds to 2 days because 2 days is closer to 36h 1 min than 36h 1 min is to 1 day.

Example

use hifitime::{Duration, TimeUnits};

assert_eq!((2.hours() + 3.minutes()).approx(), 2.hours());
assert_eq!((24.hours() + 3.minutes()).approx(), 1.days());
assert_eq!((35.hours() + 59.minutes()).approx(), 1.days());
assert_eq!((36.hours() + 1.minutes()).approx(), 2.days());
assert_eq!((47.hours() + 3.minutes()).approx(), 2.days());
assert_eq!((49.hours() + 3.minutes()).approx(), 2.days());

pub fn min(self, other: Duration) -> Duration

use hifitime::TimeUnits;

let d0 = 20.seconds();
let d1 = 21.seconds();

assert_eq!(d0, d1.min(d0));
assert_eq!(d0, d0.min(d1));

pub fn max(self, other: Duration) -> Duration

Returns the maximum of the two durations.

use hifitime::TimeUnits;

let d0 = 20.seconds();
let d1 = 21.seconds();

assert_eq!(d1, d1.max(d0));
assert_eq!(d1, d0.max(d1));

pub const fn is_negative(&self) -> bool

Returns whether this is a negative or positive duration.

Trait Implementations

impl Add<Duration> for Epoch

type Output = Epoch

The resulting type after applying the + operator.

fn add(self, duration: Duration) -> Epoch

Performs the + operation.

impl Add<Unit> for Duration

type Output = Duration

The resulting type after applying the + operator.

fn add(self, rhs: Unit) -> Duration

Performs the + operation.

impl Add for Duration

fn add(self, rhs: Duration) -> Duration

Addition of Durations

Durations are centered on zero duration. Of the tuple, only the centuries may be negative, the nanoseconds are always positive and represent the nanoseconds into the current centuries.

Examples

• Duration { centuries: 0, nanoseconds: 1 } is a positive duration of zero centuries and one nanosecond.
• Duration { centuries: -1, nanoseconds: 1 } is a negative duration representing “one century before zero minus one nanosecond”

type Output = Duration

The resulting type after applying the + operator.

impl AddAssign<Duration> for Epoch

fn add_assign(&mut self, duration: Duration)

Performs the += operation.

impl AddAssign<Unit> for Duration

fn add_assign(&mut self, rhs: Unit)

Performs the += operation.

impl AddAssign for Duration

fn add_assign(&mut self, rhs: Duration)

Performs the += operation.

impl Clone for Duration

fn clone(&self) -> Duration

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Duration

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for Duration

fn default() -> Duration

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Duration

Available on crate feature serde only.

fn deserialize<D>( deserializer: D, ) -> Result<Duration, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Duration

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Div<f64> for Duration

type Output = Duration

The resulting type after applying the / operator.

fn div(self, q: f64) -> <Duration as Div<f64>>::Output

Performs the / operation.

impl Div<i64> for Duration

type Output = Duration

The resulting type after applying the / operator.

fn div(self, q: i64) -> <Duration as Div<i64>>::Output

Performs the / operation.

impl From<Duration> for Duration

fn from(hf_duration: Duration) -> Duration

Converts a Duration into a core::time::Duration

Limitations

1. If the Duration is negative, this will return a core::time::Duration::ZERO.
2. If the Duration is Duration::MAX, this will return the equivalent of [core::time::Duration::from_secs(103407943680000)]

impl From<Duration> for Duration

fn from(core_duration: Duration) -> Duration

Converts a core::time::Duration into a Duration

Limitations

1. If the core::time::Duration is larger than Duration::MAX, this will return Duration::MAX

impl FromStr for Duration

fn from_str(s_in: &str) -> Result<Duration, <Duration as FromStr>::Err>

Attempts to convert a simple string to a Duration. Does not yet support complicated durations.

Identifiers:

• d, days, day
• h, hours, hour
• min, mins, minute
• s, second, seconds
• ms, millisecond, milliseconds
• us, microsecond, microseconds
• ns, nanosecond, nanoseconds
• + or - indicates a timezone offset

Example

use hifitime::{Duration, Unit};
use std::str::FromStr;

assert_eq!(Duration::from_str("1 d").unwrap(), Unit::Day * 1);
assert_eq!(Duration::from_str("10.598 days").unwrap(), Unit::Day * 10.598);
assert_eq!(Duration::from_str("10.598 min").unwrap(), Unit::Minute * 10.598);
assert_eq!(Duration::from_str("10.598 us").unwrap(), Unit::Microsecond * 10.598);
assert_eq!(Duration::from_str("10.598 seconds").unwrap(), Unit::Second * 10.598);
assert_eq!(Duration::from_str("10.598 nanosecond").unwrap(), Unit::Nanosecond * 10.598);
assert_eq!(Duration::from_str("5 h 256 ms 1 ns").unwrap(), 5 * Unit::Hour + 256 * Unit::Millisecond + Unit::Nanosecond);
assert_eq!(Duration::from_str("-01:15:30").unwrap(), -(1 * Unit::Hour + 15 * Unit::Minute + 30 * Unit::Second));
assert_eq!(Duration::from_str("+3615").unwrap(), 36 * Unit::Hour + 15 * Unit::Minute);
assert_eq!(Duration::from_str("-5 h 256 ms 1 ns").unwrap(), -(5 * Unit::Hour + 256 * Unit::Millisecond + Unit::Nanosecond));

type Err = HifitimeError

The associated error which can be returned from parsing.

impl Hash for Duration

fn hash<H>(&self, hasher: &mut H)

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl LowerExp for Duration

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Mul<f64> for Duration

type Output = Duration

The resulting type after applying the * operator.

fn mul(self, q: f64) -> <Duration as Mul<f64>>::Output

Performs the * operation.

impl Mul<i64> for Duration

type Output = Duration

The resulting type after applying the * operator.

fn mul(self, q: i64) -> <Duration as Mul<i64>>::Output

Performs the * operation.

impl Neg for Duration

type Output = Duration

The resulting type after applying the - operator.

fn neg(self) -> <Duration as Neg>::Output

Performs the unary - operation.

impl Ord for Duration

fn cmp(&self, other: &Duration) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq<Unit> for Duration

fn eq(&self, unit: &Unit) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq for Duration

fn eq(&self, other: &Duration) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd<Unit> for Duration

fn partial_cmp(&self, unit: &Unit) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrd for Duration

fn partial_cmp(&self, other: &Duration) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for Duration

Available on crate feature serde only.

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl Sub<Duration> for Epoch

type Output = Epoch

The resulting type after applying the - operator.

fn sub(self, duration: Duration) -> Epoch

Performs the - operation.

impl Sub<Unit> for Duration

type Output = Duration

The resulting type after applying the - operator.

fn sub(self, rhs: Unit) -> Duration

Performs the - operation.

impl Sub for Duration

fn sub(self, rhs: Duration) -> Duration

Subtraction

This operation is a notch confusing with negative durations. As described in the Duration structure, a Duration of (-1, NANOSECONDS_PER_CENTURY-1) is closer to zero than (-1, 0).

Algorithm

A > B, and both are positive

If A > B, then A.centuries is subtracted by B.centuries, and A.nanoseconds is subtracted by B.nanoseconds. If an overflow occurs, e.g. A.nanoseconds < B.nanoseconds, the number of nanoseconds is increased by the number of nanoseconds per century, and the number of centuries is decreased by one.

use hifitime::{Duration, NANOSECONDS_PER_CENTURY};

let a = Duration::from_parts(1, 1);
let b = Duration::from_parts(0, 10);
let c = Duration::from_parts(0, NANOSECONDS_PER_CENTURY - 9);
assert_eq!(a - b, c);

A < B, and both are positive

In this case, the resulting duration will be negative. The number of centuries is a signed integer, so it is set to the difference of A.centuries - B.centuries. The number of nanoseconds however must be wrapped by the number of nanoseconds per century. For example:, let A = (0, 1) and B = (1, 10), then the resulting duration will be (-2, NANOSECONDS_PER_CENTURY - (10 - 1)). In this case, the centuries are set to -2 because B is two centuries into the future (the number of centuries into the future is zero-indexed).

use hifitime::{Duration, NANOSECONDS_PER_CENTURY};

let a = Duration::from_parts(0, 1);
let b = Duration::from_parts(1, 10);
let c = Duration::from_parts(-2, NANOSECONDS_PER_CENTURY - 9);
assert_eq!(a - b, c);

A > B, both are negative

In this case, we try to stick to normal arithmatics: (-9 - -10) = (-9 + 10) = +1. In this case, we can simply add the components of the duration together. For example, let A = (-1, NANOSECONDS_PER_CENTURY - 2), and B = (-1, NANOSECONDS_PER_CENTURY - 1). Respectively, A is two nanoseconds before Duration::ZERO and B is one nanosecond before Duration::ZERO. Then, A-B should be one nanoseconds before zero, i.e. (-1, NANOSECONDS_PER_CENTURY - 1). This is because we subtract “negative one nanosecond” from a “negative minus two nanoseconds”, which corresponds to adding the opposite, and the opposite of “negative one nanosecond” is “positive one nanosecond”.

use hifitime::{Duration, NANOSECONDS_PER_CENTURY};

let a = Duration::from_parts(-1, NANOSECONDS_PER_CENTURY - 9);
let b = Duration::from_parts(-1, NANOSECONDS_PER_CENTURY - 10);
let c = Duration::from_parts(0, 1);
assert_eq!(a - b, c);

A < B, both are negative

Just like in the prior case, we try to stick to normal arithmatics: (-10 - -9) = (-10 + 9) = -1.

use hifitime::{Duration, NANOSECONDS_PER_CENTURY};

let a = Duration::from_parts(-1, NANOSECONDS_PER_CENTURY - 10);
let b = Duration::from_parts(-1, NANOSECONDS_PER_CENTURY - 9);
let c = Duration::from_parts(-1, NANOSECONDS_PER_CENTURY - 1);
assert_eq!(a - b, c);

MIN is the minimum

One cannot subtract anything from the MIN.

use hifitime::Duration;

let one_ns = Duration::from_parts(0, 1);
assert_eq!(Duration::MIN - one_ns, Duration::MIN);

type Output = Duration

The resulting type after applying the - operator.

impl SubAssign<Duration> for Epoch

fn sub_assign(&mut self, duration: Duration)

Performs the -= operation.

impl SubAssign<Unit> for Duration

fn sub_assign(&mut self, rhs: Unit)

Performs the -= operation.

impl SubAssign for Duration

fn sub_assign(&mut self, rhs: Duration)

Performs the -= operation.

impl Copy for Duration

impl Eq for Duration