sum14.java

数值分析之计算方法与实验1舍入误差与数值稳定性 by java

class Sum14{
  //从大到小
  public static double bts(double N){
     double sum=0.0;
     for(double j=2;j<=N;j++) sum=sum+1/(j*j-1);    
     System.out.println(sum);
     return sum;
   }
   //从小到大
   public static double stb(double N){
      double sum=0;
      for(double j=N;j>=2;j--)sum=sum+1/(j*j-1);       
      
      System.out.println(sum);
      return sum;
   }
   //精确值 
   public static double jingque(double N){      
      double s=0.5*(1.5-1/N-1/(N+1));      
      System.out.println(s);
      return s;
   }   	  
  public static void main(String[]args){
    System.out.print("1000精确值");
    double j1=jingque(1000);
    System.out.print("从小到大");
    double s1=stb(1000);
    System.out.print("从大到小");
    double b1=bts(1000);
    
    System.out.print("10000精确值");
     j1=jingque(10000);
    System.out.print("从小到大");
    s1=stb(10000);
    System.out.print("从大到小");
     b1=bts(10000);
    
    System.out.print("30000精确值");
    j1=jingque(30000);
    System.out.print("从小到大");
     s1=stb(30000);
    System.out.print("从大到小");
     b1=bts(30000);   
  }
}