SLA_SEP - Angle Between 2 Points on Sphere   

ACTION:

Angle between two points on a sphere (single precision).

CALL:

R = sla_SEP (A1, B1, A2, B2)

GIVEN:

A1,B1 spherical coordinates of one point (radians)

A2,B2 R spherical coordinates of the other point (radians)

RETURNED:

sla_SEP angle between [A1,B1] and [A2,B2] in radians

NOTES:

1.

The spherical coordinates are right ascension and declination, longitude and latitude, etc. in radians.

2.

The result is always positive.