relativePosition function

double relativePosition(
  1. double ra1,
  2. double dec1,
  3. double ra2,
  4. double dec2,
)

Position angle from point 1 to point 2.

Implementation

double relativePosition(double ra1, double dec1, double ra2, double dec2) {
  final sDra = math.sin(ra2 - ra1);
  final cDra = math.cos(ra2 - ra1);
  return math.atan2(sDra, math.cos(dec1) * math.tan(dec2) -
      math.sin(dec1) * cDra);
}