stp@T61:~$
stp@T61:~$ cat hup_atan2.c
#include "stdio.h"
#include "math.h"
#define N1 27278059051902.5
#define N2 29996016632198.0
void main( void )
{
printf("The arc tangent for %lf and %lf is %lf\n", N1, N2, atan2(N1, N2) );
}
stp@T61:~$ gcc hup_atan2.c
stp@T61:~$ ./a.out
The arc tangent for 27278059051902.500000 and 29996016632198.000000 is 0.737978
stp@T61:~$
------------------
atan2
double atan2 ( double y, double x );
long double atan2 ( long double y, long double x );
float atan2 ( float y, float x );
Compute arc tangent with two parameters
Returns the principal value of the arc tangent of y/x, expressed in radians.