[R-sig-Geo] function for bearing

[Michael Sumner]

>
> There is a very interesting discussion of the centrality of 
> azimuth-finding in the development of mathematics and mathematical 
> geography in: http://patriot.net/users/abdali/ftp/qibla.pdf. Among others, 
> al-Khwarizmi was an important contributor.
>
>   
Thanks Roger - that is a really excellent resource. A similar one by 
Sudipto Banerjee for distance that I learnt a lot from is here:

http://www.biostat.umn.edu/~sudiptob/ResearchPapers/Geodesics.pdf