Compute the Radian on C pgm

#include

#include

float toRadian (float angle)

 {

  float const PI = atan(1.0)*4.0;

  return(angle * PI / 180.0);

}

float computeDist (float lat1, float long1, float lat2, float long2) 

{

  float const R = 3964.0;

  float temp;

  temp = sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(long1-long2);

  return(2.0 * R * atan(sqrt((1.0-temp)/(1.0+temp))));

}

void main ()

 {

  float lat1, long1, lat2, long2, distance;

  cout << "Enter lat1, long1: ";

  cin >> lat1 >> long1;

  cout << "Enter lat2, long2: ";

  cin >> lat2 >> long2;

  distance = computeDist(toRadian(lat1), 

                                      toRadian(long1), 

                                      toRadian(lat2),

                                      toRadian(long2));

  cout << "Distance = " << distance << endl;

}