GEO-Search: The Haversine Equation

To calculate longitude & latitude of an area easiest way is to calculate The "Haversine Equation".
Implementation of this equation in various programming language was done at here ->

http://blog.fedecarg.com/2009/02/08/geo-proximity-search-the-haversine-equation/

I port it in basic C programming ->

 #include <stdio.h>  
 #include <math.h>  
 double deg2rad(double lat);  
 int main()  
 {  
 double curr_long=-2.708077,curr_lat = 53.754842;  
 int radius=20;  
 double denominator = cos(deg2rad(curr_lat)) * 69;  // 69 as calculation in Mile
 double min_long = curr_long - (radius / denominator );  
 double max_long = curr_long + (radius / denominator );  
 double min_lat = curr_lat - (double)radius / 69;  
 double max_lat = curr_lat + (double)radius / 69;  
 printf("Minimum Longitude :%1.9f\nMaximum Longitude: %1.9f\n",min_long,max_long);  
 printf("Minimum Latitude :%1.9f\nMaximum Latitude: %1.9f\n",min_lat,max_lat);  
 return 0;  
 }  
 double deg2rad(double lat)  
 {  
 return 0.0174532925*lat;  
 }