error in calculating the parallactic angle of the moon bright limb in MoonPosition.swift

[djmlewis]

There is an error in calculating the parallactic angle of the moon bright limb in MoonPosition.swift

In MoonPosition.swift line 88 the closing bracket for the atan2() function comes too early:

88 let pa = atan2(sin(h), tan(phi) * cos(mc.getTheta())) - sin(mc.getTheta()) * cos(h)

The atan2() closing bracket should come after the final cos(h), instead it comes after cos(mc.getTheta()))<== this bracket closes atan2()

This formula (based on formula 14.1 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998) is correct in the original Javascript by mourner (who confusingly has abbreviated the atan2() function to "atan"):
https://github.com/mourner/suncalc/blob/master/suncalc.js

215 pa = atan(sin(H), tan(phi) * cos(c.dec) - sin(c.dec) * cos(H));

and in the Java translation by shred:
https://github.com/shred/commons-suncalc/blob/master/src/main/java/org/shredzone/commons/suncalc/MoonPosition.java

90 double pa = atan2(sin(h), tan(phi) * cos(mc.getTheta()) - sin(mc.getTheta()) * cos(h));

The pa calculation is omitted in the Swift translation by shanus on which many other Swift versions are based

https://github.com/shanus/suncalc-swift/blob/master/suncalc/suncalc.swift