auto merge of #14090 : TeXitoi/rust/shootout-nbody-improvement, r=alexcrichton
- minimize bound check - factorise operations - use x, y, z instead of [f64, ..3] - ~1.15 faster
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2877a4e989
@ -8,8 +8,6 @@
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use std::os;
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static PI: f64 = 3.141592653589793;
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static SOLAR_MASS: f64 = 4.0 * PI * PI;
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static YEAR: f64 = 365.24;
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@ -18,151 +16,143 @@ static N_BODIES: uint = 5;
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static BODIES: [Planet, ..N_BODIES] = [
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// Sun
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Planet {
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x: [ 0.0, 0.0, 0.0 ],
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v: [ 0.0, 0.0, 0.0 ],
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x: 0.0, y: 0.0, z: 0.0,
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vx: 0.0, vy: 0.0, vz: 0.0,
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mass: SOLAR_MASS,
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},
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// Jupiter
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Planet {
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x: [
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4.84143144246472090e+00,
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-1.16032004402742839e+00,
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-1.03622044471123109e-01,
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],
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v: [
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1.66007664274403694e-03 * YEAR,
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7.69901118419740425e-03 * YEAR,
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-6.90460016972063023e-05 * YEAR,
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],
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x: 4.84143144246472090e+00,
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y: -1.16032004402742839e+00,
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z: -1.03622044471123109e-01,
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vx: 1.66007664274403694e-03 * YEAR,
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vy: 7.69901118419740425e-03 * YEAR,
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vz: -6.90460016972063023e-05 * YEAR,
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mass: 9.54791938424326609e-04 * SOLAR_MASS,
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},
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// Saturn
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Planet {
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x: [
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8.34336671824457987e+00,
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4.12479856412430479e+00,
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-4.03523417114321381e-01,
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],
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v: [
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-2.76742510726862411e-03 * YEAR,
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4.99852801234917238e-03 * YEAR,
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2.30417297573763929e-05 * YEAR,
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],
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x: 8.34336671824457987e+00,
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y: 4.12479856412430479e+00,
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z: -4.03523417114321381e-01,
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vx: -2.76742510726862411e-03 * YEAR,
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vy: 4.99852801234917238e-03 * YEAR,
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vz: 2.30417297573763929e-05 * YEAR,
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mass: 2.85885980666130812e-04 * SOLAR_MASS,
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},
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// Uranus
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Planet {
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x: [
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1.28943695621391310e+01,
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-1.51111514016986312e+01,
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-2.23307578892655734e-01,
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],
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v: [
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2.96460137564761618e-03 * YEAR,
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2.37847173959480950e-03 * YEAR,
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-2.96589568540237556e-05 * YEAR,
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],
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x: 1.28943695621391310e+01,
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y: -1.51111514016986312e+01,
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z: -2.23307578892655734e-01,
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vx: 2.96460137564761618e-03 * YEAR,
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vy: 2.37847173959480950e-03 * YEAR,
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vz: -2.96589568540237556e-05 * YEAR,
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mass: 4.36624404335156298e-05 * SOLAR_MASS,
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},
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// Neptune
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Planet {
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x: [
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1.53796971148509165e+01,
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-2.59193146099879641e+01,
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1.79258772950371181e-01,
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],
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v: [
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2.68067772490389322e-03 * YEAR,
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1.62824170038242295e-03 * YEAR,
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-9.51592254519715870e-05 * YEAR,
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],
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x: 1.53796971148509165e+01,
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y: -2.59193146099879641e+01,
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z: 1.79258772950371181e-01,
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vx: 2.68067772490389322e-03 * YEAR,
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vy: 1.62824170038242295e-03 * YEAR,
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vz: -9.51592254519715870e-05 * YEAR,
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mass: 5.15138902046611451e-05 * SOLAR_MASS,
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},
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];
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struct Planet {
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x: [f64, ..3],
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v: [f64, ..3],
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x: f64, y: f64, z: f64,
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vx: f64, vy: f64, vz: f64,
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mass: f64,
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}
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fn advance(bodies: &mut [Planet, ..N_BODIES], dt: f64, steps: i32) {
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let mut d = [ 0.0, ..3 ];
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fn advance(bodies: &mut [Planet, ..N_BODIES], dt: f64, steps: int) {
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for _ in range(0, steps) {
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for i in range(0u, N_BODIES) {
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for j in range(i + 1, N_BODIES) {
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d[0] = bodies[i].x[0] - bodies[j].x[0];
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d[1] = bodies[i].x[1] - bodies[j].x[1];
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d[2] = bodies[i].x[2] - bodies[j].x[2];
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{
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let mut b_slice = bodies.as_mut_slice();
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loop {
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let bi = match b_slice.mut_shift_ref() {
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Some(bi) => bi,
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None => break
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};
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for bj in b_slice.mut_iter() {
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let dx = bi.x - bj.x;
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let dy = bi.y - bj.y;
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let dz = bi.z - bj.z;
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let d2 = d[0]*d[0] + d[1]*d[1] + d[2]*d[2];
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let mag = dt / (d2 * d2.sqrt());
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let d2 = dx * dx + dy * dy + dz * dz;
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let mag = dt / (d2 * d2.sqrt());
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let a_mass = bodies[i].mass;
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let b_mass = bodies[j].mass;
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bodies[i].v[0] -= d[0] * b_mass * mag;
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bodies[i].v[1] -= d[1] * b_mass * mag;
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bodies[i].v[2] -= d[2] * b_mass * mag;
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bi.vx -= dx * bj.mass * mag;
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bi.vy -= dy * bj.mass * mag;
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bi.vz -= dz * bj.mass * mag;
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bodies[j].v[0] += d[0] * a_mass * mag;
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bodies[j].v[1] += d[1] * a_mass * mag;
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bodies[j].v[2] += d[2] * a_mass * mag;
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bj.vx += dx * bi.mass * mag;
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bj.vy += dy * bi.mass * mag;
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bj.vz += dz * bi.mass * mag;
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}
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}
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}
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for a in bodies.mut_iter() {
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a.x[0] += dt * a.v[0];
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a.x[1] += dt * a.v[1];
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a.x[2] += dt * a.v[2];
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for bi in bodies.mut_iter() {
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bi.x += dt * bi.vx;
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bi.y += dt * bi.vy;
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bi.z += dt * bi.vz;
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}
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}
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}
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fn energy(bodies: &[Planet, ..N_BODIES]) -> f64 {
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let mut e = 0.0;
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let mut d = [ 0.0, ..3 ];
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for i in range(0u, N_BODIES) {
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for k in range(0u, 3) {
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e += bodies[i].mass * bodies[i].v[k] * bodies[i].v[k] / 2.0;
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}
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for j in range(i + 1, N_BODIES) {
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for k in range(0u, 3) {
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d[k] = bodies[i].x[k] - bodies[j].x[k];
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}
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let dist = (d[0]*d[0] + d[1]*d[1] + d[2]*d[2]).sqrt();
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e -= bodies[i].mass * bodies[j].mass / dist;
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let mut bodies = bodies.as_slice();
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loop {
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let bi = match bodies.shift_ref() {
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Some(bi) => bi,
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None => break
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};
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e += (bi.vx * bi.vx + bi.vy * bi.vy + bi.vz * bi.vz) * bi.mass / 2.0;
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for bj in bodies.iter() {
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let dx = bi.x - bj.x;
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let dy = bi.y - bj.y;
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let dz = bi.z - bj.z;
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let dist = (dx * dx + dy * dy + dz * dz).sqrt();
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e -= bi.mass * bj.mass / dist;
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}
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}
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e
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}
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fn offset_momentum(bodies: &mut [Planet, ..N_BODIES]) {
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for i in range(0u, N_BODIES) {
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for k in range(0u, 3) {
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bodies[0].v[k] -= bodies[i].v[k] * bodies[i].mass / SOLAR_MASS;
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}
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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 bodies.iter() {
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px += bi.vx * bi.mass;
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py += bi.vy * bi.mass;
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pz += bi.vz * bi.mass;
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}
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let sun = &mut bodies[0];
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sun.vx = - px / SOLAR_MASS;
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sun.vy = - py / SOLAR_MASS;
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sun.vz = - pz / SOLAR_MASS;
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}
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fn main() {
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let args = os::args();
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let args = if os::getenv("RUST_BENCH").is_some() {
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vec!("".to_owned(), "1000".to_owned())
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} else if args.len() <= 1u {
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vec!("".to_owned(), "1000".to_owned())
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let n = if std::os::getenv("RUST_BENCH").is_some() {
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5000000
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} else {
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args.move_iter().collect()
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std::os::args().as_slice().get(1)
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.and_then(|arg| from_str(*arg))
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.unwrap_or(1000)
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};
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let n: i32 = from_str::<i32>(*args.get(1)).unwrap();
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let mut bodies = BODIES;
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offset_momentum(&mut bodies);
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println!("{:.9f}", energy(&bodies) as f64);
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println!("{:.9f}", energy(&bodies));
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advance(&mut bodies, 0.01, n);
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println!("{:.9f}", energy(&bodies) as f64);
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println!("{:.9f}", energy(&bodies));
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}
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