Added some benchmarking and small performance improvements

benches/orbit.rs

@@ -0,0 +1,40 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+
+use differential_equations::prelude::*;
+use nalgebra::Vector6;
+
+fn bench_orbit(c: &mut Criterion) {
+    let mu = 3.98600441500000e14;
+
+    // Set up the system
+    type Params = (f64,);
+    let params = (mu,);
+    fn derivative(_t: f64, state: Vector6<f64>, p: &Params) -> Vector6<f64> {
+        let acc = -(p.0 * state.fixed_rows::<3>(0)) / (state.fixed_rows::<3>(0).norm().powi(3));
+        Vector6::new(state[3], state[4], state[5], acc[0], acc[1], acc[2])
+    }
+    let y0 = Vector6::new(
+        4.263868426884883e6,
+        5.146189057155391e6,
+        1.1310208421331816e6,
+        -5923.454461876975,
+        4496.802639690076,
+        1870.3893008991558,
+    );
+
+    // Integrate
+    let ode = ODE::new(&derivative, 0.0, 86400.0, y0, params);
+    let dp45 = DormandPrince45::new(1e-8_f64, 1e-8_f64);
+    let controller = PIController::new(0.37, 0.04, 10.0, 0.2, 1000.0, 0.9, 0.01);
+
+    c.bench_function("bench_orbit", |b| {
+        b.iter(|| {
+            std::hint::black_box({
+                Problem::new(ode, dp45, controller).solve();
+            });
+        });
+    });
+}
+
+criterion_group!(benches, bench_orbit);
+criterion_main!(benches);