| // +build ignore |
| |
| /* |
| Redistribution and use in source and binary forms, with or without |
| modification, are permitted provided that the following conditions are met: |
| |
| * Redistributions of source code must retain the above copyright |
| notice, this list of conditions and the following disclaimer. |
| |
| * Redistributions in binary form must reproduce the above copyright |
| notice, this list of conditions and the following disclaimer in the |
| documentation and/or other materials provided with the distribution. |
| |
| * Neither the name of "The Computer Language Benchmarks Game" nor the |
| name of "The Computer Language Shootout Benchmarks" nor the names of |
| its contributors may be used to endorse or promote products derived |
| from this software without specific prior written permission. |
| |
| THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| * The Great Computer Language Shootout |
| * http://shootout.alioth.debian.org/ |
| * |
| * contributed by Christoph Bauer |
| * |
| */ |
| |
| #include <math.h> |
| #include <stdio.h> |
| #include <stdlib.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 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 |
| } |
| }; |
| |
| int main(int argc, char ** argv) |
| { |
| int n = atoi(argv[1]); |
| int i; |
| |
| 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)); |
| return 0; |
| } |