PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ z_to_latitude()

double z_to_latitude ( double  z,
int  top 
)

Used in great circle to compute the pole of the great circle.

Definition at line 997 of file lwgeodetic.c.

References FP_IS_ZERO, LWDEBUGF, and SIGNUM.

Referenced by clairaut_cartesian(), and clairaut_geographic().

998 {
999  double sign = SIGNUM(z);
1000  double tlat = acos(z);
1001  LWDEBUGF(4, "inputs: z(%.8g) sign(%.8g) tlat(%.8g)", z, sign, tlat);
1002  if (FP_IS_ZERO(z))
1003  {
1004  if (top) return M_PI_2;
1005  else return -1.0 * M_PI_2;
1006  }
1007  if (fabs(tlat) > M_PI_2 )
1008  {
1009  tlat = sign * (M_PI - fabs(tlat));
1010  }
1011  else
1012  {
1013  tlat = sign * tlat;
1014  }
1015  LWDEBUGF(4, "output: tlat(%.8g)", tlat);
1016  return tlat;
1017 }
#define FP_IS_ZERO(A)
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:55
#define SIGNUM(n)
Macro that returns: -1 if n < 0, 1 if n > 0, 0 if n == 0.
Here is the caller graph for this function: