Question

java编程π＝4*(1-1/3+1/5-1/7+1/9-…-1/(2*i-1)+1/(2*i+1)) 当i=10,100，1000时的π值

Answer 1

import java.util.Scanner;
public class NewEmpty{
public static void main(String[] args) {
double PI=0.0;
int i;
System.out.println("输入i的值");
Scanner sc=new Scanner(System.in);
i=sc.nextInt();//输入位数
int t=0;
while(t<=i){
if(t%2==0){
PI=PI+1/(2.0*t+1);
}
else if(t%2==1){
PI=PI-1/(2.0*t+1);
}
t++;
}
System.out.println("π="+4*PI);
}
}
i值是多少自己可以选择

Answer 2

public static void main(String[] args) {
double pi = 0.0;
int n = 1000; //当n=10,100，1000
int flag = 1;
for(int i=0;i<=n+1;i++){
if(i%2==1)
flag = -1;
else
flag = 1;
pi += flag/(2.0*i+1);
}
System.out.println("π = "+ 4*pi);
}