444 lines
10 KiB
Rust
444 lines
10 KiB
Rust
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use std::{
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collections::{BTreeMap, HashMap},
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time::Instant,
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};
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fn main () {
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// PUC Lua is 250 ms
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// I'm using AOT Rust here so anything more than that
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// is simply embarrassing
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fn timer <F: Fn ()> (f: F, label: &str) {
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let start = Instant::now ();
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f ();
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let stop = Instant::now ();
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println! ("{}: {} ms", label, (stop - start).as_millis ());
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}
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timer (|| n_body::<BTreeTable> (100000), "BTreeTable");
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timer (|| n_body::<BTreeTable2> (100000), "BTreeTable2");
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timer (|| n_body::<HashTable> (100000), "HashTable");
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timer (|| n_body_2::<HashTable2> (100000), "HashTable2");
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timer (|| n_body_2::<BTreeTable3> (100000), "BTreeTable3");
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}
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trait Table {
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fn get (&self, key: &str) -> f64;
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fn set (&mut self, key: &'static str, value: f64);
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}
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#[derive (Default)]
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struct BTreeTable (BTreeMap <String, f64>);
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impl Table for BTreeTable {
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fn get (&self, key: &str) -> f64 {
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*self.0.get (key).unwrap ()
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}
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fn set (&mut self, key: &str, value: f64) {
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self.0.insert (key.to_string (), value);
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}
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}
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#[derive (Default)]
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struct BTreeTable2 (BTreeMap <&'static str, f64>);
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impl Table for BTreeTable2 {
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fn get (&self, key: &str) -> f64 {
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*self.0.get (key).unwrap ()
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}
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fn set (&mut self, key: &'static str, value: f64) {
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self.0.insert (key, value);
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}
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}
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#[derive (Default)]
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struct HashTable (HashMap <String, f64>);
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impl Table for HashTable {
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fn get (&self, key: &str) -> f64 {
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*self.0.get (key).unwrap ()
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}
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fn set (&mut self, key: &str, value: f64) {
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self.0.insert (key.to_string (), value);
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}
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}
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const PI: f64 = 3.141592653589793f64;
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const SOLAR_MASS: f64 = 4.0 * PI * PI;
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fn n_body <T: Default + Table> (num_iters: usize) {
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const X: &str = "x";
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const Y: &str = "y";
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const Z: &str = "z";
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const VX: &str = "vx";
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const VY: &str = "vy";
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const VZ: &str = "vz";
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const MASS: &str = "mass";
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let days_per_year = 365.24;
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let mut bodies = vec! [];
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{
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let mut t = T::default ();
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t.set (X, 0.0);
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t.set (Y, 0.0);
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t.set (Z, 0.0);
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t.set (VX, 0.0);
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t.set (VY, 0.0);
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t.set (VZ, 0.0);
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t.set (MASS, SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 4.84143144246472090e+00);
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t.set (Y, -1.16032004402742839e+00);
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t.set (Z, -1.03622044471123109e-01);
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t.set (VX, 1.66007664274403694e-03 * days_per_year);
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t.set (VY, 7.69901118419740425e-03 * days_per_year);
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t.set (VZ, -6.90460016972063023e-05 * days_per_year);
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t.set (MASS, 9.54791938424326609e-04 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 8.34336671824457987e+00);
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t.set (Y, 4.12479856412430479e+00);
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t.set (Z, -4.03523417114321381e-01);
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t.set (VX, -2.76742510726862411e-03 * days_per_year);
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t.set (VY, 4.99852801234917238e-03 * days_per_year);
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t.set (VZ, 2.30417297573763929e-05 * days_per_year);
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t.set (MASS, 2.85885980666130812e-04 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 1.28943695621391310e+01);
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t.set (Y, -1.51111514016986312e+01);
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t.set (Z, -2.23307578892655734e-01);
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t.set (VX, 2.96460137564761618e-03 * days_per_year);
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t.set (VY, 2.37847173959480950e-03 * days_per_year);
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t.set (VZ, -2.96589568540237556e-05 * days_per_year);
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t.set (MASS, 4.36624404335156298e-05 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 1.53796971148509165e+01);
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t.set (Y, -2.59193146099879641e+01);
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t.set (Z, 1.79258772950371181e-01);
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t.set (VX, 2.68067772490389322e-03 * days_per_year);
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t.set (VY, 1.62824170038242295e-03 * days_per_year);
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t.set (VZ, -9.51592254519715870e-05 * days_per_year);
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t.set (MASS, 5.15138902046611451e-05 * SOLAR_MASS);
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bodies.push (t);
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}
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fn advance <T: Table> (bodies: &mut [T], dt: f64) {
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let nbody = bodies.len ();
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for i in 0..nbody {
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let bix;
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let biy;
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let biz;
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let bimass;
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let mut bivx;
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let mut bivy;
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let mut bivz;
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{
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let bi = &mut bodies [i];
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bix = bi.get (X);
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biy = bi.get (Y);
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biz = bi.get (Z);
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bimass = bi.get (MASS);
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bivx = bi.get (VX);
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bivy = bi.get (VY);
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bivz = bi.get (VZ);
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}
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for j in i + 1..nbody {
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let bj = &mut bodies [j];
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let dx = bix - bj.get (X);
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let dy = biy - bj.get (Y);
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let dz = biz - bj.get (Z);
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let mut mag = (dx * dx + dy * dy + dz * dz).sqrt ();
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mag = dt / (mag * mag * mag);
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let mut bm = bj.get (MASS) * mag;
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bivx -= dx * bm;
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bivy -= dy * bm;
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bivz -= dz * bm;
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bm = bimass * mag;
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bj.set (VX, bj.get (VX) + dx * bm);
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bj.set (VY, bj.get (VY) + dy * bm);
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bj.set (VZ, bj.get (VZ) + dz * bm);
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}
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let bi = &mut bodies [i];
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bi.set (VX, bivx);
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bi.set (VY, bivy);
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bi.set (VZ, bivz);
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bi.set (X, bix + dt * bivx);
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bi.set (Y, biy + dt * bivy);
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bi.set (Z, biz + dt * bivz);
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}
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}
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fn energy <T: Table> (bodies: &[T]) -> f64 {
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let mut e = 0.0;
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for (i, bi) in bodies.iter ().enumerate () {
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let vx = bi.get (VX);
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let vy = bi.get (VY);
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let vz = bi.get (VZ);
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let bim = bi.get (MASS);
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e += 0.5 * bim * (vx * vx + vy * vy + vz * vz);
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for j in i + 1..bodies.len () {
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let bj = &bodies [j];
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let dx = bi.get (X) - bj.get (X);
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let dy = bi.get (Y) - bj.get (Y);
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let dz = bi.get (Z) - bj.get (Z);
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let distance = (dx * dx + dy * dy + dz * dz).sqrt ();
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e -= (bim * bj.get (MASS)) / distance;
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}
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}
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e
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}
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fn offset_momentum <T: Table> (b: &mut [T]) {
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let mut px = 0.0;
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let mut py = 0.0;
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let mut pz = 0.0;
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for bi in b.iter () {
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let bim = bi.get (MASS);
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px += bi.get (VX) * bim;
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py += bi.get (VY) * bim;
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pz += bi.get (VZ) * bim;
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}
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let bimass = b [0].get (MASS);
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b [0].set (VX, -px / bimass);
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b [0].set (VY, -py / bimass);
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b [0].set (VZ, -pz / bimass);
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}
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offset_momentum (&mut bodies);
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println! ("{:0.9}", energy (&bodies));
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for _ in 0..num_iters {
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advance (&mut bodies, 0.01);
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}
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println! ("{:0.9}", energy (&bodies));
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}
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trait Table2 {
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fn get (&self, key: i64) -> f64;
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fn set (&mut self, key: i64, value: f64);
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}
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#[derive (Default)]
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struct BTreeTable3 (BTreeMap <i64, f64>);
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impl Table2 for BTreeTable3 {
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fn get (&self, key: i64) -> f64 {
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*self.0.get (&key).unwrap ()
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}
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fn set (&mut self, key: i64, value: f64) {
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self.0.insert (key, value);
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}
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}
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#[derive (Default)]
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struct HashTable2 (HashMap <i64, f64>);
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impl Table2 for HashTable2 {
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fn get (&self, key: i64) -> f64 {
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*self.0.get (&key).unwrap ()
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}
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fn set (&mut self, key: i64, value: f64) {
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self.0.insert (key, value);
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}
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}
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fn n_body_2 <T: Default + Table2> (num_iters: usize) {
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const X: i64 = 1;
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const Y: i64 = 2;
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const Z: i64 = 3;
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const VX: i64 = 4;
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const VY: i64 = 5;
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const VZ: i64 = 6;
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const MASS: i64 = 7;
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let days_per_year = 365.24;
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let mut bodies = vec! [];
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{
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let mut t = T::default ();
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t.set (X, 0.0);
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t.set (Y, 0.0);
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t.set (Z, 0.0);
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t.set (VX, 0.0);
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t.set (VY, 0.0);
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t.set (VZ, 0.0);
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t.set (MASS, SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 4.84143144246472090e+00);
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t.set (Y, -1.16032004402742839e+00);
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t.set (Z, -1.03622044471123109e-01);
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t.set (VX, 1.66007664274403694e-03 * days_per_year);
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t.set (VY, 7.69901118419740425e-03 * days_per_year);
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t.set (VZ, -6.90460016972063023e-05 * days_per_year);
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t.set (MASS, 9.54791938424326609e-04 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 8.34336671824457987e+00);
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t.set (Y, 4.12479856412430479e+00);
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t.set (Z, -4.03523417114321381e-01);
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t.set (VX, -2.76742510726862411e-03 * days_per_year);
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t.set (VY, 4.99852801234917238e-03 * days_per_year);
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t.set (VZ, 2.30417297573763929e-05 * days_per_year);
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t.set (MASS, 2.85885980666130812e-04 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 1.28943695621391310e+01);
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t.set (Y, -1.51111514016986312e+01);
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t.set (Z, -2.23307578892655734e-01);
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t.set (VX, 2.96460137564761618e-03 * days_per_year);
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t.set (VY, 2.37847173959480950e-03 * days_per_year);
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t.set (VZ, -2.96589568540237556e-05 * days_per_year);
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t.set (MASS, 4.36624404335156298e-05 * SOLAR_MASS);
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bodies.push (t);
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}
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{
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let mut t = T::default ();
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t.set (X, 1.53796971148509165e+01);
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t.set (Y, -2.59193146099879641e+01);
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t.set (Z, 1.79258772950371181e-01);
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t.set (VX, 2.68067772490389322e-03 * days_per_year);
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t.set (VY, 1.62824170038242295e-03 * days_per_year);
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t.set (VZ, -9.51592254519715870e-05 * days_per_year);
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t.set (MASS, 5.15138902046611451e-05 * SOLAR_MASS);
|
||
|
|
|
||
|
|
bodies.push (t);
|
||
|
|
}
|
||
|
|
|
||
|
|
fn advance <T: Table2> (bodies: &mut [T], dt: f64) {
|
||
|
|
let nbody = bodies.len ();
|
||
|
|
|
||
|
|
for i in 0..nbody {
|
||
|
|
let bix;
|
||
|
|
let biy;
|
||
|
|
let biz;
|
||
|
|
let bimass;
|
||
|
|
let mut bivx;
|
||
|
|
let mut bivy;
|
||
|
|
let mut bivz;
|
||
|
|
{
|
||
|
|
let bi = &mut bodies [i];
|
||
|
|
bix = bi.get (X);
|
||
|
|
biy = bi.get (Y);
|
||
|
|
biz = bi.get (Z);
|
||
|
|
bimass = bi.get (MASS);
|
||
|
|
bivx = bi.get (VX);
|
||
|
|
bivy = bi.get (VY);
|
||
|
|
bivz = bi.get (VZ);
|
||
|
|
}
|
||
|
|
|
||
|
|
for j in i + 1..nbody {
|
||
|
|
let bj = &mut bodies [j];
|
||
|
|
let dx = bix - bj.get (X);
|
||
|
|
let dy = biy - bj.get (Y);
|
||
|
|
let dz = biz - bj.get (Z);
|
||
|
|
let mut mag = (dx * dx + dy * dy + dz * dz).sqrt ();
|
||
|
|
mag = dt / (mag * mag * mag);
|
||
|
|
let mut bm = bj.get (MASS) * mag;
|
||
|
|
bivx -= dx * bm;
|
||
|
|
bivy -= dy * bm;
|
||
|
|
bivz -= dz * bm;
|
||
|
|
bm = bimass * mag;
|
||
|
|
bj.set (VX, bj.get (VX) + dx * bm);
|
||
|
|
bj.set (VY, bj.get (VY) + dy * bm);
|
||
|
|
bj.set (VZ, bj.get (VZ) + dz * bm);
|
||
|
|
}
|
||
|
|
|
||
|
|
let bi = &mut bodies [i];
|
||
|
|
bi.set (VX, bivx);
|
||
|
|
bi.set (VY, bivy);
|
||
|
|
bi.set (VZ, bivz);
|
||
|
|
bi.set (X, bix + dt * bivx);
|
||
|
|
bi.set (Y, biy + dt * bivy);
|
||
|
|
bi.set (Z, biz + dt * bivz);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
fn energy <T: Table2> (bodies: &[T]) -> f64 {
|
||
|
|
let mut e = 0.0;
|
||
|
|
for (i, bi) in bodies.iter ().enumerate () {
|
||
|
|
let vx = bi.get (VX);
|
||
|
|
let vy = bi.get (VY);
|
||
|
|
let vz = bi.get (VZ);
|
||
|
|
let bim = bi.get (MASS);
|
||
|
|
|
||
|
|
e += 0.5 * bim * (vx * vx + vy * vy + vz * vz);
|
||
|
|
|
||
|
|
for j in i + 1..bodies.len () {
|
||
|
|
let bj = &bodies [j];
|
||
|
|
let dx = bi.get (X) - bj.get (X);
|
||
|
|
let dy = bi.get (Y) - bj.get (Y);
|
||
|
|
let dz = bi.get (Z) - bj.get (Z);
|
||
|
|
let distance = (dx * dx + dy * dy + dz * dz).sqrt ();
|
||
|
|
e -= (bim * bj.get (MASS)) / distance;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
e
|
||
|
|
}
|
||
|
|
|
||
|
|
fn offset_momentum <T: Table2> (b: &mut [T]) {
|
||
|
|
let mut px = 0.0;
|
||
|
|
let mut py = 0.0;
|
||
|
|
let mut pz = 0.0;
|
||
|
|
|
||
|
|
for bi in b.iter () {
|
||
|
|
let bim = bi.get (MASS);
|
||
|
|
px += bi.get (VX) * bim;
|
||
|
|
py += bi.get (VY) * bim;
|
||
|
|
pz += bi.get (VZ) * bim;
|
||
|
|
}
|
||
|
|
|
||
|
|
let bimass = b [0].get (MASS);
|
||
|
|
b [0].set (VX, -px / bimass);
|
||
|
|
b [0].set (VY, -py / bimass);
|
||
|
|
b [0].set (VZ, -pz / bimass);
|
||
|
|
}
|
||
|
|
|
||
|
|
offset_momentum (&mut bodies);
|
||
|
|
println! ("{:0.9}", energy (&bodies));
|
||
|
|
for _ in 0..num_iters {
|
||
|
|
advance (&mut bodies, 0.01);
|
||
|
|
}
|
||
|
|
println! ("{:0.9}", energy (&bodies));
|
||
|
|
}
|