Expand description
Spherical coordinates to direction cosines
Arguments: a = double (Given) Spherical coordinate in radians (ra, long etc). b = double (Given) Spherical coordinate in radians (dec, lat etc). v = double[3] (Returned) x, y, z vector Description: The spherical coordinates are longitude (+ve anticlockwise looking from the +ve latitude pole) and latitude. The Cartesian coordinates are right handed, with the x axis at zero longitude and latitude, and the z axis at the +ve latitude pole. Notes:
- Uses eraS2c(). See SOFA/ERFA documentation for details.
Original: https://github.com/Starlink/pal/blob/7af65f05fcd33fd7362c586eae7e98972cb03f29/palOne2One.c#L368
Safety
v will be modified