并行计算--Java--求π并行实现

  public void run()
 {

   int i;
   step=1.0/(double)num_steps_wy;
   for(i=start_wy;i<num_steps_wy;i+=2)
   {
    x=(i+0.5)*step;
    sum=sum+4.0/(1.0+x*x);
   }

  }
  public void seril_pi()
  {
   int i;
   step=1.0/(double)num_steps_wy;
   for(i=1;i<num_steps_wy;i++)
   {
    x=(i+0.5)*step;
    sum=sum+4.0/(1.0+x*x);
   }
  }

  public static void main(String[] args) throws InterruptedException {

   double pi_wy,sum_wy=0.0,seri_t_wy,para_t_wy;


   Pi_thread thread1=new Pi_thread(1);
   Pi_thread thread2=new Pi_thread(2);

   double t1=System.currentTimeMillis();

   thread1.start();
   thread2.start();
   thread1.join();
   thread2.join();

   double t2=System.currentTimeMillis();

   sum_wy=thread1.sum+thread2.sum;
   pi_wy=thread1.step*sum_wy;
   para_t_wy=t2-t1;
   System.out.println("并行结果: "+pi_wy);
   System.out.println("并行时间: "+para_t_wy);

   Pi_thread thread3=new Pi_thread(3);

   t1=System.currentTimeMillis();

   thread3.seril_pi();

   t2=System.currentTimeMillis();

   pi_wy=thread3.sum*thread3.step;

   seri_t_wy=t2-t1;
   System.out.println("窜行结果： "+pi_wy);
   System.out.println("串行时间： "+seri_t_wy);
   System.out.println("加速比： "+(seri_t_wy/para_t_wy));

  }

 }

并行结果: 3.1415926135900225
并行时间: 484.0
窜行结果： 3.1415926135904266
串行时间： 1000.0
加速比： 2.0661157024793386

  public void run()
 {

   int i;
   step=1.0/(double)num_steps_wy;
   for(i=start_wy;i<num_steps_wy;i+=2)
   {
    x=(i+0.5)*step;
    sum=sum+4.0/(1.0+x*x);
   }

  }
  public void seril_pi()
  {
   int i;
   step=1.0/(double)num_steps_wy;
   for(i=1;i<num_steps_wy;i++)
   {
    x=(i+0.5)*step;
    sum=sum+4.0/(1.0+x*x);
   }
  }

  public static void main(String[] args) throws InterruptedException {

   double pi_wy,sum_wy=0.0,seri_t_wy,para_t_wy;


   Pi_thread thread1=new Pi_thread(1);
   Pi_thread thread2=new Pi_thread(2);

   double t1=System.currentTimeMillis();

   thread1.start();
   thread2.start();
   thread1.join();
   thread2.join();

   double t2=System.currentTimeMillis();

   sum_wy=thread1.sum+thread2.sum;
   pi_wy=thread1.step*sum_wy;
   para_t_wy=t2-t1;
   System.out.println("并行结果: "+pi_wy);
   System.out.println("并行时间: "+para_t_wy);

   Pi_thread thread3=new Pi_thread(3);

   t1=System.currentTimeMillis();

   thread3.seril_pi();

   t2=System.currentTimeMillis();

   pi_wy=thread3.sum*thread3.step;

   seri_t_wy=t2-t1;
   System.out.println("窜行结果： "+pi_wy);
   System.out.println("串行时间： "+seri_t_wy);
   System.out.println("加速比： "+(seri_t_wy/para_t_wy));

  }

 }

并行结果: 3.1415926135900225
并行时间: 484.0
窜行结果： 3.1415926135904266
串行时间： 1000.0
加速比： 2.0661157024793386