西北工业大学软件学院计算智能方法实验粒子群算法.zip

/** * @author lbx1998 * 求二元函数：f(x,y) = x^3 + 3xy^2 - 15x - 12y 的最大值 */ public class EX { int n; //粒子数量 ParticleState[] p; //粒子数组 ParticleState[] v; //速度数组 ParticleState[] pbest; //粒子最优解 ParticleState gbest; //全局最优解 double vmax; //最大速度 int c1,c2; //学习参数 public static void main(String[] args) { EX e = new EX(); e.init(); e.PSO(200); } //适应函数 public void fitnessFunction() { for(int i = 0; i<n; i++) { p[i].f = p[i].x*p[i].x*p[i].x + 3*p[i].x*p[i].y*p[i].y - 15*p[i].x -12*p[i].y; } } //初始化 public void init() { n = 1000; p = new ParticleState[n]; v = new ParticleState[n]; pbest = new ParticleState[n]; gbest = new ParticleState(0.0, 0.0); c1=c2=3; vmax = 0.1; for(int i=0;i<n;i++) { p[i]=new ParticleState(Math.random(),Math.random()); v[i]=new ParticleState(Math.random()*vmax,Math.random()*vmax); } fitnessFunction(); //初始化粒子与集群的最优值 gbest.f = Integer.MIN_VALUE; for(int i=0;i<n;i++) { pbest[i]=p[i]; if(p[i].f > gbest.f) { gbest = p[i]; } } System.out.println("初始最优值：" +gbest.x+" "+gbest.y+" "+" "+gbest.f); } //粒子群算法 max-迭代次数 public void PSO(int max) { for(int i=0;i<max;i++) { double w = 0.3;//惯性权重 for(int j=0;j<n;j++) { //更新粒子速度 double vx=w*v[j].x+c1*Math.random()*(pbest[j].x-p[j].x)+c2*Math.random()*(gbest.x-p[j].x); double vy=w*v[j].y+c1*Math.random()*(pbest[j].y-p[j].y)+c2*Math.random()*(gbest.y-p[j].y); if (vx>vmax) vx=vmax; if (vy>vmax) vy=vmax; v[j] = new ParticleState(vx,vy); //更新粒子的位置 p[j].x += v[j].x; p[j].y += v[j].y; } fitnessFunction(); //更新个体极值和群体极值 for(int j=0;j<n;j++) { if(p[i].f > pbest[i].f) { pbest[i] = p[i]; } if(p[i].f > gbest.f) { gbest = p[i]; } } System.out.println("==="+i+"=== "+gbest.x+" "+gbest.y+" "+" "+gbest.f); } } } //粒子的状态类 class ParticleState{ public double x; public double y; public double f;//适应度，即求解函数值 ParticleState(double x, double y) { this.x = x; this.y = y; } }