N-bodysimulationusingopenMPinC。

N-体模拟是一种模拟天体运动的方法，通过计算多个天体之间的力和加速度来预测它们的运动。使用OpenMP编写并行代码，可以加快模拟速度。以下是一个使用OpenMP在C语言中进行N体模拟的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <omp.h>

#define G 6.673e-11

typedef struct {
    double x,y,z;
} vector;

typedef struct {
    vector pos, vel, f;
    double mass;
} body;

int main(int argc, char **argv)
{
    int n,i,j;
    double dt;
    body *bodies;
    vector *f;

    // 读取n和dt
    scanf("%d %lf", &n, &dt);

    // 分配内存
    bodies = (body*)malloc(n*sizeof(body));
    f = (vector*)malloc(n*sizeof(vector));

    // 读取天体信息
    for (i=0; i<n; i++) {
        scanf("%lf %lf %lf %lf %lf %lf %lf", &bodies[i].pos.x, &bodies[i].pos.y, &bodies[i].pos.z, &bodies[i].vel.x, &bodies[i].vel.y, &bodies[i].vel.z, &bodies[i].mass);
        bodies[i].f.x = bodies[i].f.y = bodies[i].f.z = 0;
    }

    // 计算加速度
    #pragma omp parallel for private(j)
    for (i=0; i<n; i++) {
        double fx, fy, fz;
        for (j=0; j<n; j++) {
            if (i != j) {
                double dx = bodies[j].pos.x - bodies[i].pos.x;
                double dy = bodies[j].pos.y - bodies[i].pos.y;
                double dz = bodies[j].pos.z - bodies[i].pos.z;
                double r = sqrt(dx*dx + dy*dy + dz*dz);
                double f = G * bodies[i].mass * bodies[j].mass / (r*r);
                fx += f * dx / r;
                fy += f * dy / r;
                fz += f * dz / r;
            }
        }
        bodies[i].f.x = fx;
        bodies[i].f.y = fy;
        bodies[i].f.z = fz;
    }

    // 更新速度和位置
    for (i=0; i<n; i++) {
        bodies[i].vel.x += dt * bodies[i].f.x / bodies[i].mass;
        bodies[i].vel.y += dt * bodies[i].f.y / bodies[i].mass;
        bodies[i].vel.z += dt * bodies[i].f.z / bodies[i].mass;
        bodies[i].pos.x += dt * bodies[i].vel.x;
        bodies[i].pos.y += dt * bodies[i].vel.y;
        bodies[i].pos.z += dt * bodies[i].vel.z;
    }

    // 输出结果
    for (i=0; i<n; i++) {
        printf("%lf %lf %lf\n", bodies[i].pos.x, bodies[i].pos.y, bodies[i].pos.z);
    }

    // 释放内存
    free(bodies);
    free(f);

    return 0;
}

该代码基于Euler的方法计算加速度，然后使用Verlet的方法更新