这是一个专门的编程语言/编译器速度测试/对比网站(http://shootout.alioth.debian.org/)给出的题目,
以下是EF源代码:
import 工具; //n-body public final class 启动类 <作者 = "liigo"> { public static main() { int n = 20000000; int time = 运行环境.取启动时间(); NBodySystem bodies = new NBodySystem(); 控制台.输出行(bodies.energy()); for (int i=0; i<n; i++) bodies.advance(0.01); 控制台.输出行(bodies.energy()); 控制台.输出行("time(ms): ", 运行环境.取启动时间() - time); 控制台.输入文本(); } } final class NBodySystem { private Body[] bodies; public init(){ bodies = new Body[5]; bodies[0] = Body.sun(); bodies[1] = Body.jupiter(); bodies[2] = Body.saturn(); bodies[3] = Body.uranus(); bodies[4] = Body.neptune(); double px = 0.0; double py = 0.0; double pz = 0.0; for(int i=0; i < bodies.长度; i++) { px += bodies[i].vx * bodies[i].mass; py += bodies[i].vy * bodies[i].mass; pz += bodies[i].vz * bodies[i].mass; } bodies[0].offsetMomentum(px,py,pz); } public advance(double dt) { for(int i=0; i < bodies.长度; i++) { Body iBody = bodies[i]; for(int j=i+1; j < bodies.长度; j++) { double dx = iBody.x - bodies[j].x; double dy = iBody.y - bodies[j].y; double dz = iBody.z - bodies[j].z; double dSquared = dx * dx + dy * dy + dz * dz; double distance = 数学运算.求平方根(dSquared); double mag = dt / (dSquared * distance); iBody.vx -= dx * bodies[j].mass * mag; iBody.vy -= dy * bodies[j].mass * mag; iBody.vz -= dz * bodies[j].mass * mag; bodies[j].vx += dx * iBody.mass * mag; bodies[j].vy += dy * iBody.mass * mag; bodies[j].vz += dz * iBody.mass * mag; } } foreach (bodies, Body body) { body.x += dt * body.vx; body.y += dt * body.vy; body.z += dt * body.vz; } } public double energy(){ double dx, dy, dz, distance; double e = 0.0; for (int i=0; i < bodies.长度; i++) { Body iBody = bodies[i]; e += 0.5 * iBody.mass * ( iBody.vx * iBody.vx + iBody.vy * iBody.vy + iBody.vz * iBody.vz ); for (int j=i+1; j < bodies.长度; j++) { Body jBody = bodies[j]; dx = iBody.x - jBody.x; dy = iBody.y - jBody.y; dz = iBody.z - jBody.z; distance = 数学运算.求平方根(dx*dx + dy*dy + dz*dz); e -= (iBody.mass * jBody.mass) / distance; } } return e; } } final class Body { const double PI = 3.141592653589793; const double SOLAR_MASS = 4 * PI * PI; const double DAYS_PER_YEAR = 365.24; public double x, y, z, vx, vy, vz, mass; public init(){} public static Body jupiter(){ Body p = new Body(); p.x = 4.84143144246472090e+00; p.y = -1.16032004402742839e+00; p.z = -1.03622044471123109e-01; p.vx = 1.66007664274403694e-03 * DAYS_PER_YEAR; p.vy = 7.69901118419740425e-03 * DAYS_PER_YEAR; p.vz = -6.90460016972063023e-05 * DAYS_PER_YEAR; p.mass = 9.54791938424326609e-04 * SOLAR_MASS; return p; } public static Body saturn(){ Body p = new Body(); p.x = 8.34336671824457987e+00; p.y = 4.12479856412430479e+00; p.z = -4.03523417114321381e-01; p.vx = -2.76742510726862411e-03 * DAYS_PER_YEAR; p.vy = 4.99852801234917238e-03 * DAYS_PER_YEAR; p.vz = 2.30417297573763929e-05 * DAYS_PER_YEAR; p.mass = 2.85885980666130812e-04 * SOLAR_MASS; return p; } public static Body uranus(){ Body p = new Body(); p.x = 1.28943695621391310e+01; p.y = -1.51111514016986312e+01; p.z = -2.23307578892655734e-01; p.vx = 2.96460137564761618e-03 * DAYS_PER_YEAR; p.vy = 2.37847173959480950e-03 * DAYS_PER_YEAR; p.vz = -2.96589568540237556e-05 * DAYS_PER_YEAR; p.mass = 4.36624404335156298e-05 * SOLAR_MASS; return p; } public static Body neptune(){ Body p = new Body(); p.x = 1.53796971148509165e+01; p.y = -2.59193146099879641e+01; p.z = 1.79258772950371181e-01; p.vx = 2.68067772490389322e-03 * DAYS_PER_YEAR; p.vy = 1.62824170038242295e-03 * DAYS_PER_YEAR; p.vz = -9.51592254519715870e-05 * DAYS_PER_YEAR; p.mass = 5.15138902046611451e-05 * SOLAR_MASS; return p; } public static Body sun(){ Body p = new Body(); p.mass = SOLAR_MASS; return p; } public Body offsetMomentum(double px, double py, double pz){ vx = -px / SOLAR_MASS; vy = -py / SOLAR_MASS; vz = -pz / SOLAR_MASS; return this; } }
这个EF程序,在我的机器上,运行耗时约 165 秒。相应的VC6最佳优化后运行耗时约 15 秒。
其它编程语言/编译器的表现,请看这里:http://shootout.alioth.debian.org/gp4/benchmark.php?test=nbody&lang=all
总的来说,EF表现不坏。比不少编程语言(如C++, JAVA, C#, D, Fortran, Pascal)慢很多,又比另外不少编程语言(如Erlang, Python, Ruby, Perl, PHP, Lua, Groovy, SmallTalk, JavaScript)快很多。
进一步分析的话:EF作为编译型语言,通常比其它编译型语言都慢(毕竟EF编译器尚未优化),最多慢10倍以上;EF通常比解释型语言都要快,往往快数倍、数十倍,以至上百倍。
还有很多测试题目,有时间再继续。想了解EF语言,请到EF官方博客:http://blog.csdn.net/efdev/