[StormcasteR]

So.Dudes heres the deal.Yesterday a friend of mine wanted me to help him with a function that calculates square root of a positive number using Newton's method.So I came up with this:

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
  const double tol = 0.000005;
  double value;
  double old_app, new_app;
  cout << "Square root of a number"
       << endl << endl;
  cout << "Enter a positive number: ";
  cin >> value;
  if (value < 0.0)
    cout << "Cannot find square root of negative number"
         << endl;
  else
     if (value == 0.0)
        cout << "square root of "
             << value
             << " is 0.00"
             << endl;
     else
       {
         old_app = value;
         new_app = (old_app + value/old_app)/2;
         while (fabs((new_app-old_app)/new_app) > tol)
           {
             old_app = new_app;
             new_app = (old_app + value/old_app)/2;
           }
         cout << "square root of "
              << value
              << " is " << new_app
              << endl;
              system ("pause");
       }
}

But I'm really new in C++ and I'm not sure if this is the right way to represent this algorithm?