[arul]

You can use the api:

double distance = mobile1.GetDistanceToSqrt(mobile2);

Anyway, if you want to compare the distance against some fixed value, rather use a power-of-two of the fixed value since square root calculations are quite expensive.

So if the original code looked like:

    public static int CalculateDistance( Mobile from, Mobile target )
    {
        int distance = Math.Sqrt( Math.Pow( from.X - target.X, 2 ) + Math.Pow( from.Y - target.Y, 2 ) );
        return distance;
    }
....
   if(CalculateDistance( m1, m2 ) > 7)
  {
     DoSomething();
  }

Then the optimized code would look like:

public static int CalculateDistanceSansSqrt(Mobile from, Mobile target)
{
     int dx= from.X - target.X;
     int dy= from.Y - target.Y;

     return (dx*dx) + (dy*dy);
}

   if(CalculateDistanceSansSqrt( m1, m2 ) > ( 7*7 )/*49*/)
  {
     DoSomething();
  }

Without the square root it turns out to be like 3.5 times faster.