PostGIS  2.5.1dev-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 1018 of file lwgeodetic.c.

References FP_IS_ZERO, LWDEBUGF, and SIGNUM.

Referenced by clairaut_cartesian(), and clairaut_geographic().

1019 {
1020  double sign = SIGNUM(z);
1021  double tlat = acos(z);
1022  LWDEBUGF(4, "inputs: z(%.8g) sign(%.8g) tlat(%.8g)", z, sign, tlat);
1023  if (FP_IS_ZERO(z))
1024  {
1025  if (top) return M_PI_2;
1026  else return -1.0 * M_PI_2;
1027  }
1028  if (fabs(tlat) > M_PI_2 )
1029  {
1030  tlat = sign * (M_PI - fabs(tlat));
1031  }
1032  else
1033  {
1034  tlat = sign * tlat;
1035  }
1036  LWDEBUGF(4, "output: tlat(%.8g)", tlat);
1037  return tlat;
1038 }
#define FP_IS_ZERO(A)
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:88
#define SIGNUM(n)
Macro that returns: -1 if n < 0, 1 if n > 0, 0 if n == 0.
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