[GRASS-dev] calculating bearing

Hamish hamish_nospam at yahoo.com
Wed May 16 04:40:06 EDT 2007

Michael Barton wrote:
> Is there a simple formula to calculate bearing if you have the
> beginning xy of a line and the ending xy of the line?

trig:  angle = atan(y/x)    [or atan2()]

see Glynn's warnings in the archives about that going undefined at places.

see also:
  g.manual m.cogo

it gets ugly with lat/lon great circle calculations as the bearing isn't
steady. (but there are map projections that help with that)

I've got some matlab functions for doing this if m.cogo isn't your cup
of tea.


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