Format

      #include  <math.h>

      double atan2  (double y, double x);

      float atan2f  (float y, float x); (Integrity servers, Alpha)

      long double atan2l  (long double y, long double x);

                          (Integrity servers, Alpha)

      double atand2  (double y, double x);

                     (Integrity servers, Alpha)

      float atand2f  (float y, float x); (Integrity servers, Alpha)

      long double atand2l  (long double y, long double x);

                           (Integrity servers, Alpha)