快速求开方

void test(int nn)
{
    const double e = 1e-6;
    double k = 10;
    double n = 2,  m = k;

            while (n - m < -e || n - m > e)
            {
                m = k / n;
                n = (m + n) / 2;
              //  cout<<n<<endl;
            }
            cout<<n<<endl;
}