用迭代法求近似平方根

//用迭代法求近似平方根
#include <iostream>
#include <cmath>

using namespace std;

int main()
{
int flag = 0;
cout<<"please enter a number:";
double a = 0.0;
cin>>a;

const double EPSTLON = 1E-14;
double xnew = a;
double xold = 0.0;

do{
xold = xnew;
xnew = (xold + a/xold)/2;
}while(fabs(xnew - xold) > EPSTLON);

cout<<"the square root is:"<<xnew<<endl;
cin>>flag;

return 0;
}

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