Initial checkin

2025-06-10 20:42:21 +02:00 · 2019-08-23 11:56:54 -07:00 · 2019-08-23 11:56:54 -07:00 · 078564ac9e
commit 078564ac9e
parent c74712dad9
3242 changed files with 1616395 additions and 0 deletions
--- a/BeefySysLib/perf_tests/nbody.cpp
+++ b/BeefySysLib/perf_tests/nbody.cpp
@ -0,0 +1,136 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "Common.h"
+
+#define pi 3.141592653589793
+#define solar_mass (4 * pi * pi)
+#define days_per_year 365.24
+
+struct planet {
+	double x, y, z;
+	double vx, vy, vz;
+	double mass;
+};
+
+void advance(int nbodies, struct planet * bodies, double dt)
+{
+	int i, j;
+
+	for (i = 0; i < nbodies; i++) {
+		struct planet * b = &(bodies[i]);
+		for (j = i + 1; j < nbodies; j++) {
+			struct planet * b2 = &(bodies[j]);
+			double dx = b->x - b2->x;
+			double dy = b->y - b2->y;
+			double dz = b->z - b2->z;
+			double distance = sqrt(dx * dx + dy * dy + dz * dz);
+			double mag = dt / (distance * distance * distance);
+			b->vx -= dx * b2->mass * mag;
+			b->vy -= dy * b2->mass * mag;
+			b->vz -= dz * b2->mass * mag;
+			b2->vx += dx * b->mass * mag;
+			b2->vy += dy * b->mass * mag;
+			b2->vz += dz * b->mass * mag;
+		}
+	}
+	for (i = 0; i < nbodies; i++) {
+		struct planet * b = &(bodies[i]);
+		b->x += dt * b->vx;
+		b->y += dt * b->vy;
+		b->z += dt * b->vz;
+	}
+}
+
+double energy(int nbodies, struct planet * bodies)
+{
+	double e;
+	int i, j;
+
+	e = 0.0;
+	for (i = 0; i < nbodies; i++) {
+		struct planet * b = &(bodies[i]);
+		e += 0.5 * b->mass * (b->vx * b->vx + b->vy * b->vy + b->vz * b->vz);
+		for (j = i + 1; j < nbodies; j++) {
+			struct planet * b2 = &(bodies[j]);
+			double dx = b->x - b2->x;
+			double dy = b->y - b2->y;
+			double dz = b->z - b2->z;
+			double distance = sqrt(dx * dx + dy * dy + dz * dz);
+			e -= (b->mass * b2->mass) / distance;
+		}
+	}
+	return e;
+}
+
+void offset_momentum(int nbodies, struct planet * bodies)
+{
+	double px = 0.0, py = 0.0, pz = 0.0;
+	int i;
+	for (i = 0; i < nbodies; i++) {
+		px += bodies[i].vx * bodies[i].mass;
+		py += bodies[i].vy * bodies[i].mass;
+		pz += bodies[i].vz * bodies[i].mass;
+	}
+	bodies[0].vx = -px / solar_mass;
+	bodies[0].vy = -py / solar_mass;
+	bodies[0].vz = -pz / solar_mass;
+}
+
+#define NBODIES 5
+struct planet orig_bodies[NBODIES] = {
+	{                               /* sun */
+		0, 0, 0, 0, 0, 0, solar_mass
+	},
+	{                               /* jupiter */
+		4.84143144246472090e+00,
+		-1.16032004402742839e+00,
+		-1.03622044471123109e-01,
+		1.66007664274403694e-03 * days_per_year,
+		7.69901118419740425e-03 * days_per_year,
+		-6.90460016972063023e-05 * days_per_year,
+		9.54791938424326609e-04 * solar_mass
+	},
+	{                               /* saturn */
+		8.34336671824457987e+00,
+		4.12479856412430479e+00,
+		-4.03523417114321381e-01,
+		-2.76742510726862411e-03 * days_per_year,
+		4.99852801234917238e-03 * days_per_year,
+		2.30417297573763929e-05 * days_per_year,
+		2.85885980666130812e-04 * solar_mass
+	},
+	{                               /* uranus */
+		1.28943695621391310e+01,
+		-1.51111514016986312e+01,
+		-2.23307578892655734e-01,
+		2.96460137564761618e-03 * days_per_year,
+		2.37847173959480950e-03 * days_per_year,
+		-2.96589568540237556e-05 * days_per_year,
+		4.36624404335156298e-05 * solar_mass
+	},
+	{                               /* neptune */
+		1.53796971148509165e+01,
+		-2.59193146099879641e+01,
+		1.79258772950371181e-01,
+		2.68067772490389322e-03 * days_per_year,
+		1.62824170038242295e-03 * days_per_year,
+		-9.51592254519715870e-05 * days_per_year,
+		5.15138902046611451e-05 * solar_mass
+	}
+};
+
+struct planet bodies[NBODIES];
+
+void NBody(int n)
+{	
+	int i;
+
+	memcpy(bodies, orig_bodies, sizeof(orig_bodies));
+
+	offset_momentum(NBODIES, bodies);
+	printf("%.9f\n", energy(NBODIES, bodies));
+	for (i = 1; i <= n; i++)
+		advance(NBODIES, bodies, 0.01);
+	printf("%.9f\n", energy(NBODIES, bodies));
+}