Chebyshev in-place evaluation

[nyx-space]

Chebyshev in-place evaluation

[ChristopherRabotin]

chbint.c should work!

[ChristopherRabotin]

Woop! This works, I just had to figure out where exactly to fetch the data. The velocity is still wrong, but the position is as good as what the other test has!

        let interval_length: f64 = exb_states.window_duration;

        let epoch_jde = epoch.as_jde_tdb_days();
        let delta_jde = epoch_jde - start_mod_julian_f64;

        let index_f = (delta_jde / interval_length).floor();
        // let mut offset = delta_jde - index_f * interval_length;
        // let index_f = (delta_jde / interval_length).floor();
        let mut offset = delta_jde - delta_jde.floor();

        // let mut offset = delta_jde - (delta_jde / interval_length).floor() * interval_length;

        let mut index = (delta_jde / interval_length).floor() as usize;
        if index == exb_states.position.len() {
            index -= 1;
            offset = interval_length;
        } else if index > exb_states.position.len() {
            return Err(NyxError::NoInterpolationData(format!(
                "No interpolation data for date {}",
                epoch
            )));
        }
        let pos_coeffs = &exb_states.position[index];

        let rcrd_radius_s = interval_length / 2.0;
        let s = (epoch_jde - (start_mod_julian_f64 + index_f * interval_length + rcrd_radius_s))
            / rcrd_radius_s;

        let s2 = 2.0 * s;
        let mut j = coefficient_count;
        let mut w = [0.0_f64; 3];
        let mut dw = [0.0_f64; 3];

        while j > 1 {
            w[2] = w[1];
            w[1] = w[0];
            w[0] = pos_coeffs.x[j - 1] + (s2 * w[1] - w[2]);

            dw[2] = dw[1];
            dw[1] = dw[0];
            dw[0] = w[1] * 2. + dw[1] * s2 - dw[2];
            j -= 1;
        }

        let x = pos_coeffs.x[0] + (s * w[0] - w[1]);
        let vx = w[0] + s * dw[0] - dw[1];

With code above, for X and VX:

[src/cosmic/cosm.rs:1120] ven2ear_state.x - 2.051_262_195_720_077_5e8 = -0.0004665851593017578
[src/cosmic/cosm.rs:1121] ven2ear_state.vx - 3.605_137_427_817_783e1 = 258.123891015126

Nominal code:

running 1 test
[src/cosmic/cosm.rs:1115] ven2ear_state.x - 2.051_262_195_720_077_5e8 = -0.0004665553569793701
[src/cosmic/cosm.rs:1116] ven2ear_state.vx - 3.605_137_427_817_783e1 = 1.9305446130601922e-10
test cosmic::cosm::tests::test_debug ... ok