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Consolidated accel and sum into Vector4 #369

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merged 2 commits into from
Oct 14, 2024
Merged

Consolidated accel and sum into Vector4 #369

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d04d502
Consolidated accel and sum into Vector4
gregjesl Oct 14, 2024
db8722f
Fixed sign error
gregjesl Oct 14, 2024
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31 changes: 13 additions & 18 deletions src/dynamics/sph_harmonics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ use snafu::ResultExt;
use crate::cosmic::{AstroPhysicsSnafu, Frame, Orbit};
use crate::dynamics::AccelModel;
use crate::io::gravity::HarmonicsMem;
use crate::linalg::{DMatrix, Matrix3, Vector3, U7};
use crate::linalg::{DMatrix, Matrix3, Vector3, Vector4, U7};
use hyperdual::linalg::norm;
use hyperdual::{hyperspace_from_vector, Float, OHyperdual};
use std::cmp::min;
Expand Down Expand Up @@ -208,16 +208,10 @@ impl AccelModel for Harmonics {

let rho = eq_radius_km / r_;
let mut rho_np1 = mu_km3_s2 / r_ * rho;
let mut a0 = 0.0;
let mut a1 = 0.0;
let mut a2 = 0.0;
let mut a3 = 0.0;
let mut accel4: Vector4<f64> = Vector4::zeros();

for n in 1..max_degree {
let mut sum0 = 0.0;
let mut sum1 = 0.0;
let mut sum2 = 0.0;
let mut sum3 = 0.0;
let mut sum: Vector4<f64> = Vector4::zeros();
rho_np1 *= rho;

for m in 0..=min(n, max_order) {
Expand All @@ -234,18 +228,19 @@ impl AccelModel for Harmonics {
(s_val * r_m[m - 1] - c_val * i_m[m - 1]) * 2.0.sqrt()
};

sum0 += (m as f64) * a_nm[(n, m)] * e_;
sum1 += (m as f64) * a_nm[(n, m)] * f_;
sum2 += self.vr01[(n, m)] * a_nm[(n, m + 1)] * d_;
sum3 += self.vr11[(n, m)] * a_nm[(n + 1, m + 1)] * d_;
sum.x += (m as f64) * a_nm[(n, m)] * e_;
sum.y += (m as f64) * a_nm[(n, m)] * f_;
sum.z += self.vr01[(n, m)] * a_nm[(n, m + 1)] * d_;
sum.w -= self.vr11[(n, m)] * a_nm[(n + 1, m + 1)] * d_;
}
let rr = rho_np1 / eq_radius_km;
a0 += rr * sum0;
a1 += rr * sum1;
a2 += rr * sum2;
a3 -= rr * sum3;
accel4 += rr * sum;
}
let accel = Vector3::new(a0 + a3 * s_, a1 + a3 * t_, a2 + a3 * u_);
let accel = Vector3::new(
accel4.x + accel4.w * s_,
accel4.y + accel4.w * t_,
accel4.z + accel4.w * u_,
);
// Rotate this acceleration vector back into the integration frame (no center change needed, it's just a vector)
// As discussed with Sai, if the Earth was spinning faster, would the acceleration due to the harmonics be any different?
// No. Therefore, we do not need to account for the transport theorem here.
Expand Down
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