rust-roche 0.4.4

Rust translation of Tom Marsh's cpp-roche package for modelling Roche distorted stars/binary systems.
Documentation 
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use crate::errors::RocheError;
use crate::{Star, Vec3};
use crate::{fblink, pot_min, ref_sphere, set_earth, sphere_eclipse};
use pyo3::prelude::*;
use std::f64::consts::TAU;

///
/// ingress_egress tests for whether a given point is eclipsed by a Roche-distorted star. If
/// it is, it computes the ingress and egress phases using a binary chop. The accuracy on the
/// phase should be set to be below the expected uncertainties of the phases of your data.
///
/// Arguments:
///
/// * `q`:       the mass ratio = M2/M1.
/// * `star`:    which star, primary or secondary, is doing the eclipsing
/// * `spin`:    ratio of spin to orbit of eclipsing star
/// * `ffac`:    linear filling factor
/// * `iangle`:  inclination angle
/// * `delta`:  the accuracy in phase wanted.
/// * `r`:       position vector of point of interest.
/// * `ingress`: ingress phase (if eclipsed)
/// * `egress`:  egress phase
///
/// Returns:
///
/// * false = not eclipsed; true = eclipsed.
///
pub fn ingress_egress(
    q: f64,
    star: Star,
    spin: f64,
    ffac: f64,
    iangle: f64,
    delta: f64,
    r: &Vec3,
    ingress: &mut f64,
    egress: &mut f64,
) -> Result<bool, RocheError> {
    let rref: f64;
    let pref: f64;
    (rref, pref) = ref_sphere(q, star, spin, ffac)?;
    let ri: f64 = iangle.to_radians();
    let (sini, cosi) = ri.sin_cos();

    let cofm: Vec3 = match star {
        Star::Primary => Vec3::cofm1(),
        Star::Secondary => Vec3::cofm2(),
    };

    let mut phi1: f64 = 0.0;
    let mut phi2: f64 = 0.0;
    let mut lam1: f64 = 0.0;
    let mut lam2: f64 = 0.0;
    let mut phi: f64 = 0.0;
    let mut lam: f64 = 0.0;

    if sphere_eclipse(
        cosi, sini, r, &cofm, rref, &mut phi1, &mut phi2, &mut lam1, &mut lam2,
    ) {
        let acc: f64 = 2. * (2.0 * TAU * (lam2 - lam1) * delta).sqrt();

        if pot_min(
            q, star, spin, cosi, sini, r, phi1, phi2, lam1, lam2, rref, pref, acc, &mut phi,
            &mut lam,
        )? {
            let mut pin: f64 = phi;
            let mut pout: f64 = phi1;
            let mut pmid: f64;

            while (pin - pout).abs() > delta {
                pmid = (pin + pout) / 2.0;
                if fblink(q, star, spin, ffac, acc, &set_earth(cosi, sini, pmid), r).unwrap() {
                    pin = pmid;
                } else {
                    pout = pmid;
                }
            }
            *ingress = (pin + pout) / 2.0;
            *ingress -= ingress.floor();

            pin = phi;
            pout = phi2;
            while (pin - pout).abs() > delta {
                pmid = (pin + pout) / 2.;
                if fblink(q, star, spin, ffac, acc, &set_earth(cosi, sini, pmid), r).unwrap() {
                    pin = pmid;
                } else {
                    pout = pmid;
                }
            }
            *egress = (pin + pout) / 2.0;
            *egress -= egress.floor();
            if *egress < *ingress {
                *egress += 1.0;
            }
            Ok(true)
        } else {
            Ok(false)
        }
    } else {
        Ok(false)
    }
}

// wrapper for python library, avoiding mutable references

///
/// ingress_egress tests for whether a given point is eclipsed by a Roche-distorted star. If
/// it is, it computes the ingress and egress phases using a binary chop. The accuracy on the
/// phase should be set to be below the expected uncertainties of the phases of your data.
///
/// \param q       the mass ratio = M2/M1.
/// \param star    which star, primary or secondary, is doing the eclipsing
/// \param spin    ratio of spin to orbit of eclipsing star
/// \param ffac    linear filling factor
/// \param iangle  inclination angle
/// \param delta   the accuracy in phase wanted.
/// \param r       position vector of point of interest.
/// \return (eclipsed, ingress_phase, egress_phase)
///
#[pyfunction]
#[pyo3(name = "ingress_egress")]
pub fn ingress_egress_wrapper(
    q: f64,
    star: Star,
    spin: f64,
    ffac: f64,
    iangle: f64,
    delta: f64,
    r: &Vec3,
) -> Result<(bool, f64, f64), RocheError> {
    let mut ingress: f64 = 0.0;
    let mut egress: f64 = 0.0;
    let eclipsed: bool = ingress_egress(
        q,
        star,
        spin,
        ffac,
        iangle,
        delta,
        r,
        &mut ingress,
        &mut egress,
    )?;
    Ok((eclipsed, ingress, egress))
}