问此编码中双精度仅为6位

EN

  double a_0_d = 2 * sqrt(3);
  double b_0_d = 3;
  double ak_d = 0, bk_d = 0;
  while ((a_0_d-b_0_d) != 0) {
      ak_d = a_0_d;
      bk_d = b_0_d;
      a_0_d = (2 * ak_d * bk_d) / (ak_d + bk_d);
      b_0_d = sqrt(a_0_d * bk_d);
      //cout << a_0_d << "     " << b_0_d << endl;
  }
  pi_double = a_0_d;
  cout << "The pi_double value at double precision is  = " << pi_double << endl;