Question

编程运行为0

#include<iostream.h>
#include<math.h>
double arc(double x)
{double sum=0,a=x,b=1,c=1;
while(fabs(c*a/b)<=1e-5)
{sum+=c*a/b;
c=(-1)*c;
a=a*x*x;
b+=2;
}
return sum;

}
void main()
{double pi;
pi=16*arc(1.0/5)-4*arc(1.0/239);
cout<<pi<<endl;

}求pi值（3.14159265）利用Arc(x)=x-x3/3+x5/5-x7/7+……直到绝对值不大于10（-5）次幂x3,x5,x7-----3,5,7为次幂

Answer 1

while(fabs(c*a/b)<=1e-5)
改为while(fabs(c*a/b)>1e-5)
试试吧！